Liquid delivery device

Abstract

The application provides a liquid delivery device, which comprises a liquid supply unit, a buffer unit and a gas pump unit. The buffer unit has a buffer cavity, a liquid exchange port, a gas exchange port and a backflow port. The gas exchange port is connected to the gas pump unit through a blowing and suction pipeline. The backflow port is connected to the liquid supply unit through a backflow pipeline. The liquid exchange port is connected to an inlet pipeline and an outlet pipeline. The backflow pipeline is provided with a first backflow valve and a second backflow valve. In a liquid pumping state, the gas pump unit pumps gas, and liquid enters the buffer cavity. The first backflow valve is opened, and the second backflow valve blocks the path of the liquid in the liquid supply unit flowing into the buffer cavity through the backflow pipeline. Then, the device enters a backflow state, and the gas pump unit stops working. The liquid in the buffer cavity that is higher than the backflow port flows into the liquid supply unit through the backflow pipeline. In a liquid delivery state, the gas pump unit blows gas into the buffer cavity, and the first backflow valve is controlled to be closed to disconnect the backflow pipeline, so that the liquid is output through the outlet pipeline. Accordingly, the device cost can be reduced, and the precision of the liquid delivery amount can be improved.

Description

Technical Field

[0001] This application relates to a liquid delivery device that can reduce costs and improve the accuracy of liquid delivery. Background Technology

[0002] When conveying corrosive liquids or organic solutions, existing technologies typically employ peristaltic pumps. However, this method has drawbacks: the hoses age and become brittle under the pressure of the pump and the corrosive effects of the conveyed liquid, drastically shortening their lifespan. This leads to high maintenance costs and an increased risk of leakage. To reduce these costs and risks, in addition to increasing the corrosion resistance of the pump tubing material, structural innovations and optimizations are also necessary.

[0003] Existing solutions include using plunger pumps or syringes, but these have high material costs. There are also solutions that use variable-direction air pumps with control valves instead of plunger pumps, but these have the disadvantage of insufficient accuracy. This requires the addition of weighing and pressure regulation modules, which increases material costs and still cannot effectively solve the problem of accurate liquid delivery.

[0004] Therefore, in the existing technology, there is a technical challenge of how to reduce costs and improve the accuracy of liquid delivery. Summary of the Invention

[0005] The purpose of this application is to provide a liquid delivery device that can reduce costs and improve the accuracy of liquid delivery. To achieve the above objective, one solution of this application is a liquid delivery device comprising a supply unit, a buffer unit, and an air pump unit. The buffer unit has a buffer chamber and a liquid exchange port, an air exchange port, and a return port connected to the buffer chamber. In a vertical direction, the return port is located between the liquid exchange port and the air exchange port. The air exchange port is connected to the air pump unit via a blow-suction pipe. The return port is connected to the supply unit via a return pipe. The liquid exchange port is connected to an inlet pipe that is unidirectionally connected to the supply unit and an outlet pipe that is unidirectionally connected to external equipment. The return pipe is equipped with a first return valve and a second return valve, the first return valve controlling the opening and closing of the return pipe. In the pumping state, the air pump unit draws air from the buffer chamber via the blow-suction pipe, causing the supply unit... The liquid in the supply unit enters the buffer chamber through the inlet pipe until the liquid in the buffer chamber covers the reflux port; during this period, the first reflux valve opens, and the second reflux valve blocks the path of the liquid in the supply unit into the buffer chamber through the reflux pipe; then, in the reflux state, the air pump unit stops working, and the liquid in the buffer chamber that has covered the reflux port flows into the supply unit through the reflux pipe; during this period, the first reflux valve opens, and the second reflux valve allows the liquid in the reflux pipe to flow into the supply unit; in the liquid delivery state, the air pump unit blows air into the buffer chamber through the blow-suction pipe, and at the same time, the air pump unit controls the first reflux valve to close to disconnect the reflux pipe, so that the liquid in the supply unit is output through the outlet pipe.

[0006] According to the aforementioned technical solution, the reflux port and reflux pipeline ensure that the liquid level in the buffer chamber remains consistent before each liquid delivery, facilitating precise control of the delivered liquid volume. Furthermore, the air pump unit controls the on / off state of the control valve while simultaneously drawing in and out air, simplifying the control structure and reducing equipment costs.

[0007] In a preferred embodiment, the first return valve is a first pneumatic on / off valve, capable of disconnecting the return pipeline under the control of the air pump unit.

[0008] According to the aforementioned technical solution, the pneumatic on / off valve has a simple structure and can achieve the on / off effect under the control of air pump suction / blowing.

[0009] In a preferred embodiment, the air pump unit includes an air pump and a switching module connected to the air pump and the blow-suction tubing respectively; the air pump has an air intake port and an air blowing port; in the liquid pumping state, the switching module is in a first mode, connecting the air intake port to the blow-suction tubing; in the liquid delivery state, the switching module is in a second mode, connecting the air intake port to the first reflux valve and the air blowing port to the blow-suction tubing.

[0010] According to the aforementioned technical solution, the switching of the switching module between different modes can realize the opening and closing of the reflux valve and the suction and blowing effects in the buffer chamber.

[0011] In a preferred embodiment, the air exchange port of the buffer unit is also connected to a pressure balancing pipeline, which is unidirectionally connected to the outside air and is equipped with a balancing valve to control the opening and closing of the pressure balancing pipeline; in the liquid pumping state, the air pump unit controls the balancing valve to close to disconnect the pressure balancing pipeline; in the return flow state, after the air pump unit stops working, the balancing valve opens, and the outside air enters the buffer chamber through the pressure balancing pipeline, so that the liquid in the buffer chamber that has submerged the return port enters the liquid supply unit through the return pipeline.

[0012] According to the aforementioned technical solution, setting up a pressure balancing pipeline can end the negative pressure state in the buffer chamber more quickly and accelerate the natural return of liquid from the return pipeline.

[0013] In a preferred embodiment, the balancing valve is a second pneumatic on / off valve. In the liquid pumping state, the air outlet of the air pump is connected to the balancing valve, thereby disconnecting the air pressure balancing pipeline.

[0014] According to the aforementioned technical solution, the opening and closing of the balance valve is controlled by the blowing action of the air pump, which simplifies the control structure and reduces equipment costs.

[0015] In a preferred embodiment, the air pump controls the mode switching of the switching module via the balance valve and the first return valve.

[0016] According to the aforementioned technical solution, the air pump controls the opening and closing of the balance valve and the first return valve, and then controls the switching module to switch between the first mode and the second mode by controlling the opening and closing of the balance valve and the first return valve. There is no need to set up additional control components for the switching module, which simplifies the control structure and saves costs.

[0017] In a preferred embodiment, the first reflux valve and the balance valve are respectively connected to a first trigger and a second trigger; the switching module has a switching valve core, and the two ends of the switching valve core are respectively connected to a first elastic element and a second elastic element, the first elastic element and the second elastic element having a predetermined allowable deformation in the moving direction of the switching valve core; it also has a first blocking part and a second blocking part that can be driven by the first trigger and the second trigger respectively.

[0018] According to the aforementioned technical solution, the first trigger and the second trigger can retract as the first return valve and the balance valve open, and can also drive the first blocking part and the second blocking part to insert forward as the first return valve and the balance valve close.

[0019] In a preferred embodiment, during the pumping state, the balancing valve is closed, the second trigger and the second blocking part are located between the switching valve core and the second elastic element, with the second blocking part being closer to the second elastic element than the second trigger; when transitioning from the pumping state to the reflux state, the balancing valve opens and causes the second trigger to disengage from between the switching valve core and the second elastic element, the second blocking part remains stationary, and the switching valve core moves under the elastic force of the first elastic element and abuts against the second blocking part, thus the switching module enters a second mode; when transitioning from the reflux state to the delivery state, as the first reflux valve closes, the first trigger causes the first blocking part to enter between the switching valve core and the second elastic element. Between the two elastic elements, the second blocking part disengages from the switching valve core and the second elastic element; the first blocking part is closer to the first elastic element relative to the first trigger; when the liquid delivery state ends, the first reflux valve opens and drives the first trigger to disengage from the switching valve core and the first elastic element, the first blocking part remains stationary, the switching valve core moves under the elastic force of the second elastic element and abuts against the first blocking part, and the switching module enters the first mode; when re-entering the liquid extraction state, as the balance valve closes, the second trigger drives the second blocking part to enter between the switching valve core and the second elastic element, and the first blocking part disengages from the switching valve core and the second elastic element.

[0020] According to the aforementioned technical solution, the suction action of the air pump can control the movement of the switching valve core by opening / closing the first return valve and the balance valve, thereby realizing the mode switching of the switching module.

[0021] In a preferred embodiment, the first blocking part and the second blocking part are connected by a transmission; during the process of the first blocking part entering between the switching valve core and the first elastic member, the first blocking part drives the second blocking part to disengage from between the switching valve core and the second elastic member; during the process of the second blocking part entering between the switching valve core and the second elastic member, the second blocking part drives the first blocking part to disengage from between the switching valve core and the first elastic member.

[0022] In a preferred embodiment, the first blocking part and the second blocking part are cross-connected to a reference shaft, and the transmission connection between the first blocking part and the second blocking part is realized via the reference shaft.

[0023] According to the aforementioned technical solution, the two blocking parts can be conveniently moved in and out alternately through the linkage between the two blocking parts.

[0024] In a preferred embodiment, the second reflux valve is a one-way valve that allows liquid to enter the liquid supply unit only from the reflux port through the reflux line.

[0025] According to the aforementioned technical solution, compared to the solution of setting two pneumatic on / off valves, the one-way valve can further simplify the structure and reduce costs.

[0026] In a preferred embodiment, the second return valve is a third pneumatic on / off valve, capable of disconnecting the return pipeline under the control of the air pump unit; and when the first return valve is open, the second return valve is closed; when the first return valve is closed, the second return valve is open.

[0027] According to the aforementioned technical solution, the air pump unit controls two return valves to alternately open and close, in order to adapt to different states of liquid pumping and liquid delivery.

[0028] In a preferred embodiment, the return line is also connected to a transition container, through which the liquid flowing out of the return port first enters the transition container and then enters the supply unit.

[0029] According to the aforementioned technical solution, the returned liquid first exists in the transition container and then gradually flows into the liquid supply unit, which can accelerate the return speed of excess liquid in the buffer chamber.

[0030] In a preferred embodiment, a baffle is provided on the side of the air vent facing the buffer cavity, and the gas blown in by the air pump unit disperses into the buffer cavity after reaching the baffle.

[0031] According to the aforementioned technical solution, the shroud makes the gas blown onto the liquid surface more uniform, avoiding the liquid surface from being blown into depressions and causing errors in the amount of liquid delivered.

[0032] In a preferred embodiment, the buffer chamber is provided with a baffle plate that crosses the air intake direction and is attached to the inner wall of the buffer chamber, and the baffle plate has a through-hole.

[0033] According to the aforementioned technical solution, the air is more evenly dispersed after passing through the baffle, avoiding the liquid surface from being blown into depressions and causing errors in the amount of liquid delivered. Attached Figure Description

[0034] To more clearly illustrate this application, the accompanying drawings will be described and explained below. Obviously, the drawings described below only illustrate certain aspects of some exemplary embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0035] Figure 1 This is a schematic diagram of the liquid extraction state in Example 1.

[0036] Figure 2 This is a schematic diagram of the liquid delivery state in Example 1.

[0037] Figure 3 This is a schematic diagram of the liquid extraction state in Example 2.

[0038] Figure 4 This is a schematic diagram of the liquid delivery state in Example 2.

[0039] Figure 5 This is a schematic diagram of the second trigger insertion during the liquid extraction process.

[0040] Figure 6 This is a schematic diagram of the second trigger backing up in the reflux state.

[0041] Figure 7 This is a schematic diagram of the first trigger insertion under liquid delivery conditions.

[0042] Figure 8 This is a schematic diagram of the first trigger retracting after the liquid delivery state ends.

[0043] Figure 9 This is a schematic diagram of the structure of the first trigger and the first blocking part.

[0044] Figure 10 This is a schematic diagram of the spoiler assembly.

[0045] Figure 11 This is a schematic diagram of the spoiler assembly.

[0046] Attached image caption:

[0047] 1. Buffer unit; 10. Buffer chamber; 11. Liquid exchange port; 110. Liquid outlet pipeline; 111. Liquid outlet check valve; 12. Air exchange port; 120. Blow-suction pipeline; 121. Air pressure balance pipeline; 122. Balance valve; 1220. Balance valve core; 1221. Balance valve plate; 1222. Balance valve spring; 1223. Balance valve air inlet; 1224. Balance valve housing; 123. Balance check valve; 13. Return port; 130. Return pipeline; 131. First return valve; 1310. First return valve core; 1311. First return valve plate; 1312. First return valve spring; 1313. First return valve suction port; 1314. First return valve housing; 132. Second reflux valve; 133 Transition container; 14 Baffle; 15 Baffle plate; 2 Air pump unit; 21 Air pump; 211 Inlet; 212 Outlet; 22 Switching module; 220 Switching valve core; 221 First port; 222 Second port; 223 Third port; 224 Fourth port; 225 Fifth port; 3 Liquid supply unit; 31 Liquid inlet pipeline; 311 Liquid inlet check valve; 41 First trigger; 411 First trigger protrusion; 42 Second trigger; 51 First elastic element; 511 First pressure block; 52 Second elastic element; 521 Second pressure block; 60 Reference shaft; 61 First blocking part; 62 Second blocking part. Detailed Implementation

[0048] Various exemplary embodiments of this application are described in detail below with reference to the accompanying drawings. The descriptions of the exemplary embodiments are merely illustrative and are in no way intended to limit the application or its application or use. This application can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the application thorough and complete, and to fully express the scope of the application to those skilled in the art. It should be noted that, unless otherwise stated, the relative arrangement of components and steps, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0049] As used in this application, the words “including” or “comprising” or similar terms mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility that it may also cover other elements.

[0050] All terms used in this application (including technical or scientific terms) have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as being interpreted with idealized or highly formalized meanings, unless explicitly defined herein.

[0051] For components, specific model numbers and other parameters of components not described in detail in this section, the interrelationships between components and control circuits, these may be considered as techniques, methods and devices known to those skilled in the art, but where appropriate, such techniques, methods and devices should be considered part of the specification.

[0052] Overall Structure

[0053] The following is for reference Figure 1 This application describes the overall structure of the liquid delivery device. Figure 1 This is a schematic diagram of the liquid extraction state in Example 1.

[0054] See Figure 1 The liquid delivery device of this application includes a liquid supply unit 3, a buffer unit 1, and an air pump unit 2. The buffer unit 1 has a buffer chamber 10 and a liquid exchange port 11, an air exchange port 12, and a return port 13 communicating with the buffer chamber 10. In the vertical direction, the return port 13 is located between the liquid exchange port 11 and the air exchange port 12. Exemplarily, in the vertical direction, the air exchange port 12 is located above the return port 13, and the return port 13 is located above the liquid exchange port 11. The buffer unit 1 is a three-way buffer bottle, and the space inside the bottle is the buffer chamber 10.

[0055] The air exchange port 12 is connected to the air pump unit 2 via the blowing and suction pipe 120; the return port 13 is connected to the liquid supply unit 3 via the return pipe 130; the liquid exchange port 11 is connected to the liquid inlet pipe 31, which is in one-way communication with the liquid supply unit 3, and the liquid outlet pipe 110, which is in one-way communication with external equipment. In this embodiment, the liquid inlet pipe 31 is equipped with a liquid inlet check valve 311, so that liquid can only enter the buffer chamber 10 from the liquid supply unit 3 in one direction, and the liquid outlet pipe 110 is equipped with a liquid outlet check valve 111, so that liquid can only flow out of the buffer chamber 10 from the liquid outlet pipe 110 in one direction.

[0056] The return pipe 130 is equipped with a first return valve 131 and a second return valve 132. The first return valve 131 can control the opening and closing of the return pipe 130. Two embodiments of the second return valve 132 will be described later.

[0057] As a preferred embodiment, the return pipe 130 is also connected to a transition container 133. The transition container 133 is located between the first return valve 131 and the second return valve 132, and has a larger space than the pipe. After the liquid in the buffer chamber 10 flows into the return pipe 130 from the return port 13, it first enters the transition container 133, and then enters the supply unit 3 from the transition container 133. The reason for this arrangement is that the flow rate of the liquid in the return pipe 130 when it enters the supply unit 3 may not be high enough, which would affect the return speed of excess liquid in the buffer chamber 10. The transition container 133 allows the liquid in the buffer chamber 10 to quickly return to the transition container 133 first, and then gradually enter the supply unit 3 from the transition container 133, ensuring that the liquid level in the buffer chamber 10 quickly returns to a position level with the return port 13.

[0058] When the liquid delivery device is in the pumping state, the air pump unit 2 draws air from the buffer chamber 10 through the suction pipe 120 to create a negative pressure, causing the liquid in the liquid supply unit 3 to enter the buffer chamber 10 through the liquid inlet pipe 31, and ensuring that the liquid in the buffer chamber 10 covers the return port 13. During this period, the first return valve 131 is open, but the second return valve 132 blocks the path of the liquid in the liquid supply unit 3 into the buffer chamber 10 through the return pipe 130.

[0059] Afterwards, the liquid delivery device enters the reflux state, the air pump unit 2 stops working, and the liquid in the buffer chamber 10 that does not pass through the reflux port 13 flows into the liquid supply unit 3 through the reflux pipeline 130 under the action of gravity; during this period, the first reflux valve 131 opens, and the second reflux valve 132 allows the liquid in the reflux pipeline 130 to flow into the liquid supply unit 3.

[0060] In the liquid delivery state of the liquid delivery device, the air pump unit 2 blows air into the buffer chamber 10 through the blowing and suction pipe 120. At the same time, the air pump unit 2 controls the first return valve 131 to close to disconnect the return pipe 130, so that the liquid in the liquid supply unit 3 is output through the liquid outlet pipe 110.

[0061] In existing technologies, peristaltic pumps are commonly used to transport corrosive liquids or organic solutions. However, the repeated crushing of the pipeline by the peristaltic pump, coupled with the corrosion from the liquid, accelerates the aging and wear of the pipeline, increasing the hassle of replacement and maintenance. While using plunger pumps or syringes reduces pipeline wear, the equipment cost is higher. Another option is to use a variable-direction air pump with a control valve, but this method suffers from insufficient precision.

[0062] In comparison, this application uses an air pump unit 2 to control the on / off state of multiple valves, which saves costs, simplifies the control structure, improves the utilization efficiency of the air pump unit 2 for air intake and blowing, and results in relatively less damage to the pipeline, reducing the hassle of replacement and maintenance.

[0063] Meanwhile, excess liquid in the buffer chamber 10 that does not reach the return port 13 flows back to the supply unit 3 naturally through the return pipe 130. The amount of liquid remaining in the buffer chamber 10 remains consistent each time, ensuring that the air pressure and liquid level in the buffer bottle 10 are consistent each time liquid is delivered, thereby improving the accuracy of the delivered liquid volume. The consideration for this design is that if it is just simple repeated suction and discharge, the liquid level in the buffer chamber 10 may rise or fall successively, which may easily cause equipment failure or increase the cumulative error. Therefore, it is necessary to have initial control over the liquid level in the buffer chamber 10. The return pipe 130 can ensure that the initial liquid level in the buffer chamber 10 is maintained at the same level as the return port 13 before each liquid delivery.

[0064] Next, combined Figure 1 , Figure 2 Example 1 will be described in detail. Figure 2 This is a schematic diagram of the liquid delivery state in Example 1.

[0065] See Figure 1 The air pump unit 2 includes an air pump 21 and a switching module 22 connected to the air pump 21 and the blow-in / blow-out pipe 120 respectively. The air pump 21 has an air inlet 211 and an air outlet 212.

[0066] The air exchange port 12 of the buffer unit 1 is also connected to a pressure balancing pipeline 121, which is used to balance the air pressure inside and outside the buffer chamber 10. The pressure balancing pipeline 121 is connected to the outside air in one direction via a balancing one-way valve 123. The balancing one-way valve 123 only allows outside air to flow into the buffer chamber 10 in one direction through the pressure balancing pipeline 121. The pressure balancing pipeline 121 is also equipped with a balancing valve 122 to control its opening and closing.

[0067] Preferably, both the first return valve 131 and the balance valve 122 are pneumatic on / off valves, capable of opening / closing under the control of the air pump 21's blowing / suction. The first return valve 131 serves as the first pneumatic on / off valve, and the balance valve 122 serves as the second pneumatic on / off valve. In this embodiment, the second return valve 132 is a one-way valve, allowing liquid to enter the supply unit 3 only from the return port 13 via the return pipe 130, and disallowing liquid from the supply unit 3 from entering the return port 13 via the return pipe 130.

[0068] For example, the switching module 22 is a two-position five-way valve with five ports that communicate with the outside. The connection between different ports is controlled by mode switching. It should be noted that the mode switching of the switching module 22 can be controlled by electromagnetic control or by other means such as the suction and blowing actions of the air pump 21. An embodiment controlled by the air pump 21 will be described later.

[0069] Specifically, such as Figure 1As shown, in the liquid extraction state, the switching module 22 is in the first mode. The air inlet 211 of the air pump 21 is connected to the suction-blowing pipeline 120, and the air outlet 212 is connected to the balance valve 122. The balance valve 122 is normally open. After the air pump 21 starts working, the air outlet 212 blows air into the balance valve 122 to create a positive pressure, thereby closing the balance valve 122 and disconnecting the air pressure balance pipeline 121. At the same time, the air inlet 211 draws air from the buffer chamber 10 through the suction-blowing pipeline 120 to create a negative pressure. At this time, due to the restriction of the second return valve 132, the liquid in the liquid supply unit 3 cannot enter the buffer chamber 10 through the return pipeline 130, but can only flow into the buffer chamber 10 from the liquid inlet pipeline 31. This avoids the situation where multiple inlets run in parallel, which would cause inconsistent pressure and inaccurate delivery.

[0070] Continue reading Figure 1 In the reflux state, the air pump 21 stops working, the air blowing port 212 no longer blows air into the balance valve 122, the balance valve 122 returns to the normally open state, and the outside air enters the buffer chamber 10 through the balance check valve 123 and the air pressure balance pipeline 121, so that the excess liquid in the buffer chamber 10 that has not passed the reflux port 13 naturally flows back into the liquid supply unit 3 through the reflux pipeline 130.

[0071] like Figure 2 As shown, in the liquid delivery state, the switching module 22 is in the second mode, connecting the suction port 211 of the air pump 21 to the first return valve 131, and the blowing port 212 to the blowing and suction pipeline 120. The balance valve 122 is no longer connected to the air pump 21 and remains in the normally open state. After the air pump 21 starts working, the blowing port 212 blows air into the buffer chamber 10 through the blowing and suction pipeline 120.

[0072] At this point, on the one hand, because the second return valve 132 is a one-way valve, the gas blown into the buffer chamber 10 cannot flow out through the return pipe 130; on the other hand, due to the restrictions of the balance one-way valve 123 and the liquid inlet one-way valve 311, the gas in the buffer chamber 10 cannot flow out through the pressure balance pipe 121, and the liquid cannot flow out through the liquid inlet pipe 31. Therefore, under the pressure of the gas blown in by the air pump 21, the liquid in the buffer chamber 10 can only be output along the liquid outlet pipe 110. This avoids the situation of multiple outlets operating in parallel, which would cause inconsistent pressure distribution and inaccurate delivery volume.

[0073] In other words, by switching the mode of the switching module 22, in addition to alternately connecting the blowing and suction pipe 120 to the suction port 211 and the blowing port 212, the air pump 21 is also alternately connected to the balance valve 122 and the first return valve 131 to control the opening and closing of the corresponding pipes, thereby achieving the corresponding liquid pumping and liquid delivery effects.

[0074] Example 2

[0075] Next, combined Figure 3 , Figure 4 Example 2 will be described in detail. Figure 3 This is a schematic diagram of the liquid extraction state in Example 2. Figure 4 This is a schematic diagram of the liquid delivery state in Example 2. Figure 3 , Figure 4 Example 2 and Figure 1 , Figure 2 The same components as those in Embodiment 1 will not be described again here.

[0076] See Figure 3 In Embodiment 2, in addition to the first return valve 131 being a pneumatic on / off valve, the second return valve 132 is also a pneumatic on / off valve, both of which can be opened / closed under the control of the air pump 21's blowing / suction. The second return valve 132 is used as the third pneumatic on / off valve, while both the first return valve 131 and the second return valve 132 are normally open.

[0077] The two ports of the switching module 22 are connected to the air inlet 211 and the air outlet 212 of the air pump 21, respectively, while the other three ports are connected to the air inlet / outlet pipe 120 and the first return valve 131 and the second return valve 132, respectively. The connection between different ports is controlled by switching modes.

[0078] Specifically, such as Figure 3 As shown, in the liquid pumping state, the switching module 22 is in the first mode, connecting the suction port 211 of the air pump 21 to the suction / blowing pipeline 120, and the blowing port 212 to the second return valve 132. After the air pump 21 starts working, the blowing port 212 blows air into the second return valve 132 to bring it to a positive pressure state, thereby closing the second return valve 132 to disconnect the return pipeline 130.

[0079] At this time, the suction port 211 draws air from the buffer chamber 10 through the suction pipe 120 to create negative pressure. Since the second return valve 132 disconnects the return pipe 130, the liquid in the liquid supply unit 3 can only flow into the buffer chamber 10 through the liquid inlet pipe 31. This avoids the situation where multiple inlets run in parallel, which would cause inconsistent pressure and inaccurate delivery.

[0080] Continue reading Figure 3 In the reflux state, the air pump 21 stops working, the air blowing port 212 no longer blows air into the second reflux valve 132, the second reflux valve 132 returns to the normally open state, and the excess liquid in the buffer chamber 10 that has not passed the reflux port 13 flows into the liquid supply unit 3 through the reflux pipeline 130 and the first reflux valve 131 and the second reflux valve 132, so that the liquid level in the buffer chamber 10 is flush with the reflux port 13.

[0081] like Figure 4As shown, in the liquid delivery state, the switching module 22 is in the second mode, connecting the suction port 211 of the air pump 21 to the first return valve 131, and the blowing port 212 to the blowing and suction pipeline 120. The second return valve 132 is no longer connected to the air pump 21 and remains in the normally open state. After the air pump 21 starts working, the blowing port 212 blows air into the buffer chamber 10 through the blowing and suction pipeline 120.

[0082] At this time, the air pump 21 draws air from the first return valve 131 through the air intake port 211, creating negative pressure. This causes the first return valve 131 to close, disconnecting the return pipeline 130. The gas blown into the buffer chamber 10 cannot flow out through the return pipeline 130. In addition, the flow direction is restricted by the liquid inlet check valve 311. Under the pressure of the gas blown in by the air pump 21, the liquid in the buffer chamber 10 can only be output along the liquid outlet pipeline 110. This avoids the situation of multiple outlets running in parallel, which would cause inconsistent pressure and inaccurate delivery.

[0083] In other words, in addition to alternately connecting the blowing and suction pipe 120 to the suction port 211 and the blowing port 212, the second embodiment also alternately connects the air pump 21 to the first return valve 131 and the second return valve 132 to control the opening and closing of the corresponding pipes, thereby achieving the corresponding liquid pumping and liquid delivery effects.

[0084] It is understood that, in Embodiment 2, a pressure balancing pipeline 121 connected to the ventilation port 12 can be provided, just like in Embodiment 1, along with a balancing check valve 123 and a balancing valve 122 provided on the pressure balancing pipeline 121. Figure 3 , Figure 4 (Not shown). In the pumping state, the switching module 22 is in the first mode. The suction port 211 of the air pump 21 is connected to the suction-blowing pipeline 120, while the blowing port 212 is simultaneously connected to the second return valve 132 and the balance valve 122. By blowing air, the second return valve 132 and the balance valve 122 are simultaneously closed, thereby disconnecting the return pipeline 130 and the air pressure balance pipeline 121 respectively. This allows the air pump 21 to smoothly draw air from the buffer chamber 10 to form a negative pressure, ensuring the pumping effect. In the return state, the air pump 21 stops working, and the balance valve 122 opens to balance the internal and external air pressure of the buffer chamber 10, ensuring rapid return of excess liquid. This is consistent with the working principle of Embodiment 1 and will not be described again.

[0085] It should be noted that in Embodiments 1 and 2, the pressure balancing pipeline 121 and the balancing valve 122 may not be included. In this way, during the reflux state, after the air pump 21 stops working, the buffer chamber 10 still ends the negative pressure state through the blowing / suction pipeline 120 and the air pump 21's own gas passage, ensuring that excess liquid in the buffer chamber 10 that has not passed the reflux port 13 naturally flows back to the liquid supply unit 3 via the reflux pipeline 130. However, as a preferred embodiment, including the pressure balancing pipeline 121 allows outside air to enter the buffer chamber 10 more quickly during the reflux state, which is more conducive to the rapid reflux of excess liquid.

[0086] In Embodiment 1, if the pressure balancing pipeline 121 and the balancing valve 122 are not installed, in the liquid pumping and reflux states, the suction port 211 of the air pump 21 is connected to the blowing and suction pipeline 120, while the blowing port 212 is temporarily vented and no longer connected to any component. This continues until the switching module 22 switches to the second mode, at which point the suction port 211 is connected to the first reflux valve 131, and the blowing port 212 is connected to the blowing and suction pipeline 120. Further details are omitted here.

[0087] Mode switching

[0088] Next, combined Figures 5-9 The principle of mode switching for the air pump 21 control switching module 22 is explained. Figure 5 This is a schematic diagram of the second trigger 42 being inserted during the liquid extraction process. Figure 6 This is a schematic diagram of the second trigger 42 backing up in the reflux state. Figure 7 This is a schematic diagram of the first trigger 41 being inserted during liquid delivery. Figure 8 This is a schematic diagram showing the retraction of the first trigger 41 after the liquid delivery state ends. Figure 9 This is a schematic diagram of the structure of the first trigger 41 and the first blocking part 61.

[0089] See Figure 5 , Figure 6 The first reflux valve 131 and the balance valve 122 are respectively connected to the first trigger 41 and the second trigger 42.

[0090] Specifically, both the first return valve 131 and the balance valve 122 are pneumatic on / off valves. The first return valve 131 has a first return valve plate 1311 for clamping the return pipe 130, a first return valve core 1310 connected to the first return valve plate 1311, and a first return valve spring 1312 connected between the first return valve plate 1311 and the first return valve housing 1314. A first trigger 41 is fixedly connected to the end of the first return valve core 1310 away from the first return valve plate 1311. Preferably, the first trigger 41 is a wedge-shaped block structure as shown in the figure for easy insertion, but it is not limited to this.

[0091] The balancing valve 122 has a balancing valve plate 1221 for clamping the air pressure balancing line 121, a balancing valve core 1220 connected to the balancing valve plate 1221, and a balancing valve spring 1222 connected between the balancing valve plate 1221 and the balancing valve housing 1224. A second trigger 42 is fixedly connected to the end of the balancing valve core 1220 away from the balancing valve plate 1221. Preferably, the second trigger 42 is a wedge-shaped structure as shown in the figure for easy insertion, but it is not actually limited to this.

[0092] The switching module 22 has a switching valve core 220 and five ports for external connection: a first port 221, a second port 222, a third port 223, a fourth port 224, and a fifth port 225. The first port 221 and the second port 222 are connected to the air pump 21's intake port 211 and exhaust port 212, respectively. The third port 223, the fourth port 224, and the fifth port 225 are connected to the balance valve 122, the air intake / exhaust pipe 120, and the first return valve 131, respectively. Specifically, the third port 223 is connected to the balance valve inlet 1223 of the balance valve 122, and the fifth port 225 is connected to the first return valve intake port 1313 of the first return valve 131.

[0093] The switching valve core 220 is a longitudinally elongated structure as shown in the figure, containing three cavities. By reciprocating the switching valve core 220, the three cavities can be moved to different positions, thereby connecting different ports and realizing the switching between the first mode and the second mode.

[0094] In practical applications, external control equipment is typically used to adjust the movement of the switching valve core 220 to achieve mode switching of the switching module 22. This inevitably increases equipment cost and system complexity. Therefore, as a preferred approach, this application utilizes an air pump 21 to control the opening and closing of the first return valve 131 and the balance valve 122. The opening and closing of the first return valve 131 and the balance valve 122 then drive the first trigger 41 and the second trigger 42 respectively to adjust the movement position of the switching valve core 220, thereby achieving mode switching.

[0095] Specifically, the two ends of the switching valve core 220 are respectively connected to a first elastic element 51 and a second elastic element 52. In this embodiment, the first elastic element 51 and the second elastic element 52 abut against the two ends of the switching valve core 220 via a first pressure block 511 and a second pressure block 521, respectively, and the first elastic element 51 and the second elastic element 52 are normally in a compressed state.

[0096] The system also includes a first blocking part 61 and a second blocking part 62 for transmission connection. The first blocking part 61 and the second blocking part 62 are cross-connected at both ends of the reference shaft 60. The reference shaft 60 extends along the moving direction of the switching valve core 220 and can be a single transmission shaft or two shafts that drive each other, as long as the transmission connection between the first blocking part 61 and the second blocking part 62 can be achieved. Here, we will only illustrate the example of the first blocking part 61 and the second blocking part 62 being connected to a single reference shaft 60.

[0097] Regarding the transmission connection between the first blocking part 61 and the second blocking part 62, it mainly involves the following: during the process of the first blocking part 61 entering between the switching valve core 220 and the first pressure block 511, the first blocking part 61 drives the second blocking part 62 to disengage from the switching valve core 220 and the second pressure block 521 via the reference shaft 60; during the process of the second blocking part 62 entering between the switching valve core 220 and the second pressure block 521, the second blocking part 62 drives the first blocking part 61 to disengage from the switching valve core 220 and the first pressure block 511 via the reference shaft 60. Therefore, the projections of the first blocking part 61 and the second blocking part 62 on the cross section perpendicular to the reference shaft 60 form a certain angle, that is, the two blocking parts are arranged intersecting axially relative to the reference shaft 60.

[0098] Next, the switching between the liquid extraction state, the reflux state, and the liquid delivery state will be explained.

[0099] See Figure 5 In the liquid-drawing state, the balance valve 122 is closed. The second trigger 42 and the second blocking part 62 are inserted between the switching valve core 220 and the second pressure block 521, with the second blocking part 62 being closer to the second pressure block 521 than the second trigger 42. This arrangement follows the sequence from the switching valve core 220 to the second trigger 42, then to the second blocking part 62, and finally to the second pressure block 521. At this time, the switching module 22 is in the first mode, with the air outlet 212 of the air pump 21 connected to the balance valve inlet 1223 of the balance valve 122, and the suction port 211 connected to the air-blowing / suction pipe 120.

[0100] See Figure 6When the system transitions from the pumping state to the reflux state, the air pump 21 stops and ceases blowing air into the balance valve inlet 1223. The balance valve core 1220 retracts away from the switching valve core 220 as the balance valve spring 1222 rebounds. On one hand, the balance valve core 1220 drives the balance valve plate 1221 to retract, releasing its clamping grip on the air pressure balance line 121 and opening the balance valve 122. On the other hand, the balance valve core 1220 drives the second trigger 42 to retract, disengaging it from the switching valve core 220 and the second pressure block 521. However, the second blocking part 62 remains stationary. The first elastic member 51, in a compressed state, pushes the switching valve core 220 towards the second pressure block 521 via the first pressure block 511, ultimately abutting against the second blocking part 62. At this time, the switching module 22 enters the second mode, the air blowing port 212 of the air pump 21 is connected to the blowing and suction pipe 120, and the air suction port 211 is connected to the first return valve suction port 1313 of the first return valve 131.

[0101] See Figure 7 When transitioning from the reflux state to the liquid delivery state, the air pump 21 starts, and the suction port 211 draws air from the suction port 1313 of the first reflux valve to create a negative pressure. The first reflux valve core 1310 is inserted forward towards the switching valve core 220. On one hand, the first reflux valve core 1310 drives the first reflux valve plate 1311 to insert forward and clamp the reflux pipeline 130 with the first reflux valve housing 1314, and the first reflux valve 131 is closed. On the other hand, the first reflux valve core 1310 drives the first trigger 41 to insert forward between the switching valve core 220 and the first pressure block 511. During the insertion of the first trigger 41, the first blocking part 61 is simultaneously driven into the space between the switching valve core 220 and the first pressure block 511, and the first blocking part 61 is closer to the first pressure block 511 than the first trigger 41, i.e., arranged in the order of switching valve core 220, first trigger 41, first pressure block 511, and first elastic member 51.

[0102] Understandably, the first trigger 41 is inserted between the switching valve core 220 and the first pressure block 511, which actually compresses the first pressure block 511, further compressing the first elastic member 51, thereby creating a space between the first pressure block 511 and the switching valve core 220. During the insertion process, the first blocking part 61 drives the second blocking part 62 to disengage from the switching valve core 220 and the second pressure block 521 via the reference shaft 60, and the second pressure block 521 re-abuts against the switching valve core 220 under the rebound of the second elastic member 52.

[0103] See Figure 8When the liquid delivery state ends, the air pump 21 stops, and the suction port 211 no longer draws air from the suction port 1313 of the first return valve. The first return valve core 1310 retracts away from the switching valve core 220 as the first return valve spring 1312 rebounds. On one hand, the first return valve core 1310 drives the first return valve plate 1311 to retract and opens the first return valve 131. On the other hand, the first return valve core 1310 drives the first trigger 41 to retract and disengage from the switching valve core 220 and the first pressure block 511. The first blocking part 61 remains stationary. Under the elastic force of the second elastic member 52, the second pressure block 521 pushes the switching valve core 220 to move and abut against the first blocking part 61, and the switching module 22 enters the first mode.

[0104] Continue reading Figure 5 When the pumping state is restarted, the air pump 21 starts, and the air outlet 212 blows air from the air inlet 1223 of the balance valve to create positive pressure. The balance valve core 1220 is inserted forward towards the switching valve core 220. On one hand, the balance valve core 1220 drives the balance valve plate 1221 to insert forward and clamp the air pressure balance pipeline 121 with the balance valve housing 1224, and the balance valve 122 is closed. On the other hand, the balance valve core 1220 drives the second trigger 42 to insert forward between the switching valve core 220 and the second pressure block 521. During the insertion of the second trigger 42, the second blocking part 62 is simultaneously driven into the space between the switching valve core 220 and the second pressure block 521, and the second blocking part 62 is closer to the second pressure block 521 than the second trigger 42.

[0105] Understandably, the second trigger 42 is inserted between the switching valve core 220 and the second pressure block 521, effectively squeezing the second pressure block 521 to further compress the second elastic member 52, thereby creating a space between the second pressure block 521 and the switching valve core 220. During the insertion process, the second blocking part 62 drives the first blocking part 61 to disengage from the switching valve core 220 and the first pressure block 511 via the reference shaft 60, and the first pressure block 511 re-aggregates against the switching valve core 220 under the rebound of the first elastic member 51.

[0106] Next, the transmission between the trigger and the blocking part will be explained in detail.

[0107] See Figure 9 The first trigger 41 has a first trigger protrusion 411 on its side. During the insertion of the first trigger 41, the first trigger protrusion 411 abuts against the first blocking part 61 and drives the first blocking part 61 to rotate, so that the first trigger 41 and the first blocking part 61 both enter between the switching valve core 220 and the first pressure block 511. The reference shaft 60 rotates accordingly and disengages the second blocking part 62 from between the switching valve core 220 and the second pressure block 521.

[0108] During the retraction of the first trigger 41, the first trigger protrusion 411 retracts and disengages from the first blocking part 61, keeping the first blocking part 61 stationary and still in contact with the first pressure block 511, thereby preventing the rebound of the first elastic member 51. The space left after the first trigger 41 retracts allows the switching valve core 220 to move towards the first elastic member 51 under the elastic force of the second elastic member 52 until it abuts against the first blocking part 61.

[0109] The transmission principle between the second trigger 42 and the second blocking part 62 is the same as that between the first trigger 41 and the first blocking part 61. A protrusion is provided on the side of the second trigger 42 to drive the second blocking part 62 forward, and disengages from the second blocking part 62 when the second trigger 42 retracts, keeping the second blocking part 62 stationary to prevent the second elastic element 52 from rebounding. This will not be repeated here.

[0110] It should be noted that, preferably, the reference shaft 60 and the first trigger 41 and the second trigger 42 are located on the same side of the switching valve core 220, so that the first trigger 41 and the second trigger 42 can respectively push the first blocking part 61 and the second blocking part 62. However, this is not a limitation; the reference shaft 60 and the first trigger 41 and the second trigger 42 can also be located on different sides of the switching valve core 220, or the first trigger 41 and the first blocking part 61 can be located on one side of the switching valve core 220, and the second trigger 42 and the second blocking part 62 can be located on the other side. As long as the transmission requirements between the triggers and the blocking parts are met, the spatial layout is not specifically limited here. Figures 5-8 The reference axis 60 and the first trigger 41 and the second trigger 42 shown are located on different sides of the switching valve core 220. This is because the 3D view was simplified when it was converted into a 2D view. It is for illustration only and is not intended to be limiting.

[0111] Furthermore, in the aforementioned Embodiment 2, the second reflux valve 132 and the balance valve 122 have the same structural principle, both being positive pressure on / off valves, which will not be described in detail here. Compared to the peristaltic pump's method of crushing the pipeline, the pneumatic on / off valve of this application only clamps the pipeline to a certain extent, and the loss or damage to the pipeline caused is negligible. Moreover, the pneumatic on / off valve does not damage the integrity of the pipeline and will not cause problems such as liquid entering the valve, crystallization, or affecting airtightness.

[0112] spoiler / spoiler

[0113] Next, combined Figure 10 , Figure 11 The spoiler 14 and spoiler 15 are described in detail. Figure 10 This is an assembly diagram of the spoiler 14. Figure 11 This is an assembly diagram of spoiler 15.

[0114] See Figure 10 As a preferred embodiment, a baffle 14 is provided on the side of the air exchange port 12 facing the buffer chamber 10. For example, the baffle 14 is fitted at the outlet of the air exchange port 12 into the buffer chamber 10. After the gas blown in from the air pump 21 reaches the baffle 14, it is dispersed and blown toward the inner wall of the buffer chamber 10, making the airflow blowing toward the liquid surface more uniform and reducing the error in the amount of liquid delivered caused by the uneven airflow causing the liquid surface to be dented.

[0115] See Figure 11 As another preferred embodiment, the buffer chamber 10 is provided with a baffle plate 15 that intersects the air intake direction of the air exchange port 12 and is attached to the inner wall of the buffer chamber 10. The baffle plate 15 has through-holes. The gas blown in from the air pump 21 is dispersed through the baffle plate 15 and passes through the various vents, making the airflow blowing towards the liquid surface more uniform and reducing the error in the amount of liquid delivered caused by uneven airflow causing the liquid surface to be dented.

[0116] The baffle 15 can be a flat plate perpendicular to the air intake direction of the vent 12, a convex plate with a higher center and lower edges as shown in the figure, or an inclined plate that slopes downwards towards the return port 13. However, the upper edge of the side of the baffle 15 closest to the return port 13 should be flush with the lower edge of the return port 13, so that the liquid above the baffle 15 can naturally return through the return port 13. When configured as the aforementioned convex plate or inclined plate, the return of excess liquid can be accelerated.

[0117] In summary, this application provides a return pipeline 130 connected to the buffer chamber 10 to precisely control the liquid volume within the buffer chamber 10 and improve the accuracy of the delivered liquid volume. Simultaneously, while the air pump 21 pumps and blows air into the buffer chamber 10, it alternately controls the opening and closing of the first return valve 131 and the balance valve 122. The opening and closing of the first return valve 131 and the balance valve 122 synchronously control the mode switching of the switching module 22. This achieves precise liquid pumping and delivery, simplifies the control system, reduces equipment costs, provides the air pump 21 with more control functions for its pumping action, and overcomes the problem of severe wear on the pipeline caused by peristaltic pumps, extending its service life.

[0118] It should be understood that the specific embodiments described above are only used to explain this application, and the scope of protection of this application is not limited thereto. Any changes, substitutions, or combinations made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be covered within the scope of protection of this application.

Claims

1. A liquid delivery device, comprising a liquid supply unit, a buffer unit, and an air pump unit, characterized in that: The buffer unit has a buffer cavity and a liquid exchange port, a gas exchange port, and a return port communicating with the buffer cavity. In the plumb line direction, the return port is located between the liquid exchange port and the gas exchange port. The air exchange port is connected to the air pump unit via a blow-suction pipe; the return port is connected to the liquid supply unit via a return pipe; the liquid exchange port is connected to an inlet pipe that is unidirectionally connected to the liquid supply unit and an outlet pipe that is unidirectionally connected to external equipment. The return pipeline is equipped with a first return valve and a second return valve, and the first return valve can control the opening and closing of the return pipeline. The air pump unit includes an air pump and a switching module connected to the air pump and the blowing / suction pipeline respectively; the air pump has an air inlet and an air outlet; In the liquid extraction state, the switching module is in a first mode, connecting the air inlet to the suction-blowing pipeline and the air outlet to the second return valve, or connecting the air outlet to the balance valve; wherein, when the air outlet is connected to the balance valve, the balance valve is located in the air pressure balance pipeline connected to the air exchange port; when the air outlet is connected to the second return valve, the second return valve is a pneumatic on / off valve; the air pump unit draws air from the buffer chamber through the suction-blowing pipeline, causing the liquid in the liquid supply unit to enter the buffer chamber through the liquid inlet pipeline until the liquid in the buffer chamber submerges the return port; during this period, the first return valve is open, and the second return valve blocks the path of the liquid in the liquid supply unit flowing into the buffer chamber through the return pipeline; Then, it enters the reflux state, the air pump unit stops working, and the liquid in the buffer chamber that has not reached the reflux port flows into the liquid supply unit through the reflux pipeline; during this period, the first reflux valve opens, and the second reflux valve allows the liquid in the reflux pipeline to flow into the liquid supply unit; In the liquid delivery state, the switching module is in the second mode, connecting the air inlet to the first reflux valve and the air outlet to the air blowing pipeline; the air pump unit blows air into the buffer chamber through the air blowing pipeline, and at the same time, the air pump unit controls the first reflux valve to close to disconnect the reflux pipeline, so that the liquid in the liquid supply unit is output through the liquid outlet pipeline.

2. The liquid delivery device according to claim 1, characterized in that: The first return valve is a first pneumatic on / off valve, which can disconnect the return pipeline under the control of the air pump unit.

3. The liquid delivery device according to claim 2, characterized in that: The air pressure balancing pipeline is unidirectionally connected to the outside air; when the air outlet is connected to the balancing valve: During liquid pumping, the air pump unit controls the balance valve to close to disconnect the air pressure balance pipeline; In the reflux state, after the air pump unit stops working, the balance valve opens, and outside air enters the buffer chamber through the air pressure balance pipeline, so that the liquid in the buffer chamber that has not reached the reflux port enters the liquid supply unit through the reflux pipeline.

4. The liquid delivery device according to claim 3, characterized in that: The balancing valve is a second pneumatic on / off valve.

5. The liquid delivery device according to claim 4, characterized in that: The air pump controls the mode switching of the switching module via the balance valve and the first return valve.

6. The liquid delivery device according to claim 5, characterized in that: The first reflux valve and the balance valve are respectively connected to a first trigger and a second trigger; The switching module has a switching valve core, and a first elastic element and a second elastic element are respectively connected to the two ends of the switching valve core. The first elastic element and the second elastic element have a specified allowable deformation in the moving direction of the switching valve core. It also has a first blocking part and a second blocking part that can be driven by the first trigger and the second trigger, respectively.

7. The liquid delivery device according to claim 6, characterized in that: In the liquid extraction state, the balance valve is closed, the second trigger and the second blocking part are located between the switching valve core and the second elastic element, and the second blocking part is closer to the second elastic element than the second trigger; When the system transitions from the pumping state to the reflux state, the balance valve opens and causes the second trigger to disengage from the switching valve core and the second elastic element. The second blocking part remains stationary, and the switching valve core moves under the elastic force of the first elastic element and abuts against the second blocking part. The switching module then enters the second mode. When switching from the reflux state to the delivery state, as the first reflux valve closes, the first trigger drives the first blocking part to enter between the switching valve core and the first elastic element, and the second blocking part disengages from between the switching valve core and the second elastic element; the first blocking part is closer to the first elastic element than the first trigger. When the liquid delivery state ends, the first reflux valve opens and drives the first trigger to disengage from the switching valve core and the first elastic element. The first blocking part remains stationary, and the switching valve core moves under the elastic force of the second elastic element and abuts against the first blocking part. The switching module enters the first mode. When the pumping state is restarted, as the balance valve is closed, the second trigger causes the second blocking part to enter between the switching valve core and the second elastic element, and the first blocking part disengages from between the switching valve core and the second elastic element.

8. The liquid delivery device according to claim 7, characterized in that: The first blocking part and the second blocking part are connected by a transmission mechanism; During the process of the first blocking part entering between the switching valve core and the first elastic member, the first blocking part drives the second blocking part to disengage from between the switching valve core and the second elastic member; During the process of the second blocking part entering between the switching valve core and the second elastic member, the second blocking part causes the first blocking part to disengage from between the switching valve core and the first elastic member.

9. The liquid delivery device according to claim 8, characterized in that: The first blocking part and the second blocking part are cross-connected to the reference shaft, and the transmission connection between the first blocking part and the second blocking part is realized through the reference shaft.

10. The liquid delivery device according to any one of claims 1-9, characterized in that: The second reflux valve is a one-way valve, which only allows liquid to enter the liquid supply unit from the reflux port through the reflux pipeline.

11. The liquid delivery device according to any one of claims 1-9, characterized in that: The second return valve is a third pneumatic on / off valve, which can disconnect the return pipeline under the control of the air pump unit; Furthermore, when the first reflux valve is open, the second reflux valve is closed; when the first reflux valve is closed, the second reflux valve is open.

12. The liquid delivery device according to any one of claims 1-9, characterized in that: The return pipeline is also connected to a transition container. The liquid flowing out of the return port first enters the transition container and then enters the liquid supply unit from the transition container.

13. The liquid delivery device according to any one of claims 1-9, characterized in that: A shroud is provided on the side of the air exchange port facing the buffer chamber. The gas blown in by the air pump unit reaches the shroud and then disperses into the buffer chamber.

14. The liquid delivery device according to any one of claims 1-9, characterized in that: The buffer chamber is provided with a baffle plate that is perpendicular to the air intake direction and fits against the inner wall of the buffer chamber. The baffle plate has a through-hole.

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