Metering liquid injection device

Abstract

The invention provides a metering liquid injection device. The metering liquid injection device comprises a piston cavity, a piston, a limiting structure and a valve assembly. The piston is axially and movably arranged in the piston cavity and divides the piston cavity into an injection cavity and a transition cavity located above the injection cavity; the transition cavity is provided with a liquid inlet used for being communicated with an external liquid storage source. A first channel and a second channel which are mutually independent are arranged at the bottom of the injection cavity; the first channel is communicated with the transition cavity; the limiting structure is arranged on one axial side of the piston cavity and used for limiting the movement stroke of the piston moving towards the transition cavity in the axial direction so as to determine the maximum volume of the injection cavity. The valve assembly is used for selectively conducting the first channel or the second channel. The piston cavity is divided into the injection cavity and the transition cavity, the first channel and the second channel which are selectively controlled by the valve assembly are arranged at the bottom of the injection cavity, and the limiting structure capable of limiting the stroke of the piston is matched, so that a pure mechanical quantitative liquid injection system completely depending on liquid pressure driving is constructed.

Description

A metering injection device Technical Field

[0001] This invention relates to the field of liquid metering injection equipment technology, and more specifically, to a metering injection device. Background Technology

[0002] The content in this section only provides background information related to this invention and may not constitute prior art.

[0003] With the increasing demands for precision farming and environmental protection in modern agriculture, the efficient and quantitative delivery of liquid fertilizers or pesticides directly to plant roots has become an important research direction in the field of agricultural equipment. Direct application to plant roots can significantly improve the utilization rate of liquid agrochemicals, reduce surface evaporation and runoff, and lower environmental pollution, which is of great significance for promoting plant growth and controlling pests and diseases.

[0004] In related technologies, most liquid injection devices that achieve the above functions employ a mechanical structure similar to an injection pump to achieve quantitative injection. A typical implementation includes: a vertically extending piston chamber, with the lower end connected to an outlet pipe and the upper end or side connected to an external liquid storage source; a piston is installed inside the piston chamber, driven by an independent cylinder, electric push rod, or other linear drive mechanism to achieve reciprocating motion. Its working process is generally as follows: first, the linear drive mechanism moves the piston upward, so that the volume of the injection chamber below the piston reaches the preset injection volume; then, liquid agrochemicals are added to the injection chamber from the external liquid storage source; finally, the piston is driven downward, forcing the liquid agrochemicals in the injection chamber out through the outlet pipe, completing one quantitative injection.

[0005] However, such solutions have at least the following obvious drawbacks in practice: 1. Complex structure and high cost: In order to achieve precise linear motion of the piston, an independent linear drive mechanism must be configured, which not only increases the mechanical complexity, size and weight of the device, but also significantly increases the manufacturing cost and maintenance difficulty.

[0006] 2. Reliance on external power and control: Linear drive mechanisms usually require external energy systems such as air sources and power supplies. In field operations, the inconvenience of power and air supply restricts the flexibility and reliability of equipment use. Summary of the Invention

[0007] In view of this, the object of the present invention is to provide a metering injection device, and more particularly an injection device that can eliminate the dependence on an independent linear drive mechanism and use the liquid pressure of liquid agrochemicals to achieve piston drive and quantitative control.

[0008] The objective of this invention is achieved through the following technical solution: This invention provides a metering injection device, comprising: a piston chamber; a piston, axially movably disposed within the piston chamber, dividing the piston chamber into an injection chamber and a transition chamber located above the injection chamber; the transition chamber having an inlet for connecting to an external liquid storage source; the bottom of the injection chamber having an independent first channel and a second channel; the first channel communicating with the transition chamber; a limiting structure disposed on one axial side of the piston chamber for axially limiting the travel distance of the piston when it moves toward the transition chamber, thereby determining the maximum volume of the injection chamber; and a valve assembly for selectively opening either the first channel or the second channel.

[0009] Optionally, the piston is connected to a limiting rod, the free end of which passes through the transition cavity and extends to the outside of the piston cavity; the limiting structure includes a limiting member; the limiting member is disposed opposite to the free end of the limiting rod, so as to limit the end point of the piston's stroke when moving toward the transition cavity by the free end of the limiting rod abutting against the limiting member; wherein, the position of the limiting member in the axial direction of the piston cavity is adjustable.

[0010] Optionally, the limiting component is a limiting nut; the limiting structure further includes a protective cylinder; the protective cylinder is coaxially disposed at the top end of the piston chamber; the limiting nut is disposed inside the protective cylinder and threadedly connected to the protective cylinder; the cylinder wall of the protective cylinder is provided with an operating port extending along its axial direction; the operating port is used to expose at least a portion of the limiting nut for operating the limiting nut to rotate.

[0011] Optionally, the outer wall of the protective cylinder is provided with scale markings.

[0012] Optionally, the first channel and the second channel are arranged sequentially along the radial direction of the injection cavity; the valve assembly includes a valve core; the valve core passes sequentially through the first channel and the second channel along the radial direction of the injection cavity; the valve core is provided with a through port; wherein the valve core is configured to move between a first working position and a second working position along the radial direction of the injection cavity; in the first working position, the through port is aligned and connected with the first channel; in the second working position, the through port is aligned and connected with the second channel.

[0013] Optionally, the valve assembly further includes a resilient reset member and an operating handle; the resilient reset member is used to resiliently hold the valve core in the first working position; the operating handle is disposed on the outer wall of the piston chamber and configured to be operable to apply a driving force to the valve core toward the second working position.

[0014] Optionally, the first channel is connected to the transition cavity via a connecting pipe; the connecting pipe is U-shaped and disposed on the outer wall of the piston cavity; the operating handle is located within the space formed by the connecting pipe and the outer wall of the piston cavity.

[0015] Optionally, the metering injection device further includes an outlet pipe connected to the second channel; the distal end of the outlet pipe is conical and sealed; and the pipe wall of the outlet pipe is provided with an outlet hole adjacent to its distal end.

[0016] Optionally, there are multiple outlet holes, which are evenly distributed along the circumference of the outlet pipe; each outlet hole extends along the axial direction of the outlet pipe.

[0017] Optionally, the outlet tube is provided with a one-way valve located upstream of the outlet hole; the one-way valve is configured to open when the liquid pressure in the injection chamber is higher than a preset value, so as to allow the fluid in the outlet tube to flow to the outlet hole.

[0018] The technical solution of this invention has at least the following advantages and beneficial effects: The metering injection device provided by this invention, by dividing the piston chamber into an injection chamber and a transition chamber, and setting a first channel and a second channel at the bottom of the injection chamber that are selectively controlled by a valve assembly, combined with a limiting structure that can limit the piston stroke, constructs a purely mechanical quantitative injection system that relies entirely on liquid pressure for drive. This design fundamentally eliminates the linear drive mechanism necessary for traditional injection devices, thereby greatly simplifying the device structure, reducing manufacturing costs and maintenance difficulty, while avoiding dependence on external power or gas sources, significantly improving the reliability and adaptability of the equipment in complex environments such as fields, and achieving low-cost, high-reliability quantitative application of pesticides to plant roots. Attached Figure Description

[0019] Figure 1 is a schematic diagram of the metering injection device provided in an embodiment of the present invention; Figure 2 is a cross-sectional view of the metering injection device shown in Figure 1; Figure 3 is an enlarged view of the structure at point A in Figure 2 and a partial enlarged view of the structure, showing the situation when the valve core is in the first working position; Figure 4 is an enlarged view of the structure at point B in Figure 1; Figure 5 is an enlarged view of the structure at point C in Figure 1; Figure 6 is an enlarged view of the structure at point D in Figure 2.

[0020] Icons: 10-Piston chamber, 11-Injection chamber, 12-Transition chamber, 13-Inlet, 14-First channel, 15-Second channel, 20-Piston, 21-Limit rod, 22-Buffer chamber, 30-Limiting structure, 31-Limiting component, 32-Buffer pad, 33-Protective cylinder, 34-Operating port, 35-Scale marking, 40-Valve assembly, 41-Valve core, 42-Conducting port, 43-Elastic reset component, 44-Operating handle, 50-Outlet pipe, 51-Outlet hole, 52-One-way valve, 60-Connecting pipeline, 70-Control valve. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. The same reference numerals in the accompanying drawings represent the same components. It should be noted that the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the described embodiments of this invention without creative effort are within the scope of protection of this invention.

[0022] Compared to the embodiments shown in the accompanying drawings, feasible embodiments within the scope of protection of this invention may have fewer components, other components not shown in the drawings, different components, components with different arrangements, or components with different connections, etc. Furthermore, two or more components in the drawings may be implemented in a single component, or a single component shown in the drawings may be implemented as multiple separate components.

[0023] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components.

[0024] Referring to Figures 1 to 6, embodiments of the present invention provide a metering injection device, particularly a device suitable for quantitatively injecting liquid agrochemicals (such as liquid fertilizers or pesticides) into plant roots. The core of the present invention lies in providing a purely mechanical solution that achieves precise and adjustable quantitative injection without requiring an external linear drive mechanism (such as a cylinder or electric actuator).

[0025] As shown in Figures 1 to 3, the metering injection device provided in this embodiment of the invention includes a piston chamber 10 extending vertically and a piston 20 axially movable within the piston chamber 10. The piston 20 divides the piston chamber 10 axially into two independent chambers, namely an injection chamber 11 and a transition chamber 12 located above the injection chamber 11.

[0026] The transition chamber 12 has an inlet 13 on its side wall for connecting to an external liquid storage source, so that liquid agrochemicals can be selectively supplied to the transition chamber 12 by the external liquid storage source. The external liquid storage source can be a backpack medicine box or other device suitable for storing liquid agrochemicals.

[0027] The bottom of the injection chamber 11 is provided with a first channel 14 and a second channel 15 that are independent of each other. The first channel 14 is connected to the transition chamber 12 through a connecting pipe 60, which will be described later. Preferably, the connection point between the first channel 14 and the transition chamber 12 is located below the liquid inlet 13.

[0028] In addition, the metering injection device also includes a limiting structure 30 and a valve assembly 40. The limiting structure 30 is disposed on one axial side (e.g., the top) of the piston chamber 10 to limit the stroke of the piston 20 as it moves toward the transition chamber 12, thereby determining the maximum volume of the injection chamber 11. The valve assembly 40 is used to selectively open either the first channel 14 or the second channel 15. That is, the valve assembly 40 is used to selectively open one of the first channel 14 and the second channel 15, and the first channel 14 and the second channel 15 will not be open simultaneously.

[0029] The metering and injection device provided in this embodiment of the invention operates by using the fluid pressure of the liquid agrochemical provided by an external storage source to drive the piston 20 to reciprocate within the piston chamber 10. The valve assembly 40 controls the switching between the first channel 14 and the second channel 15, and the limiting structure 30 limits the stroke of the piston 20, thereby achieving precise quantitative and cyclic injection of the liquid agrochemical. Specifically, the workflow of this metering and injection device is as follows: In the initial state, the valve assembly 40 opens the first channel 14 and simultaneously closes the second channel 15. The external storage source (e.g., a backpack medicine box) is connected to the inlet 13 via a pipeline. When the operator turns on the external storage source, the liquid agrochemical from the external storage source enters the transition chamber 12 through the inlet 13. After the liquid agrochemical enters the transition chamber 12, it applies downward hydraulic pressure to the upper surface of the piston 20, pushing the piston 20 downward toward the injection chamber 11 until the piston 20 reaches its lower limit position, for example, contacting the bottom of the injection chamber 11. Thereafter, the liquid agrochemical continues to flow into the transition chamber 12. When the liquid level in the transition chamber 12 reaches the point where the first channel 14 connects to the transition chamber 12, the liquid agrochemical will enter the lower injection chamber 11 through the first channel 14. As the amount of liquid agrochemical in the injection chamber 11 increases, the pressure inside the injection chamber 11 will gradually rise. Since the transition chamber 12 is connected to a low-pressure external liquid source through the inlet 13, and the injection chamber 11 is in a relatively closed state with the second channel 15 closed, the pressure inside the injection chamber 11 will continuously rise and exceed the pressure inside the transition chamber 12. This pressure difference creates an upward force acting on the lower surface of the piston 20, driving the piston 20 upward. When the piston 20 moves upward until it is blocked by the limiting structure 30, the piston 20 stops moving. At this time, the injection chamber 11 is just filled with the predetermined volume of liquid agrochemical, thus completing the quantitative liquid storage process.

[0030] Subsequently, the operator can operate valve assembly 40 to close the first channel 14 and simultaneously open the second channel 15. At this time, the connection between injection chamber 11 and transition chamber 12 is severed. External liquid agrochemicals continue to flow into transition chamber 12, causing the pressure inside transition chamber 12 to rise rapidly. The increased pressure acts on the upper surface of piston 20, pushing piston 20 downward. The downward movement of piston 20 compresses the metered amount of liquid agrochemicals stored in injection chamber 11, forcing the liquid agrochemicals in injection chamber 11 to be discharged outward through the second channel 15. Finally, it can be injected into the soil where the plant roots are located through an outlet pipe 50 (described in detail later) connected to the second channel 15, thus completing one metered injection operation. After one metered injection operation is completed, valve assembly 40 is switched back to its initial state to prepare for the next operation cycle.

[0031] As can be seen, the metering injection device provided in this embodiment of the invention, through the above-described configuration, constructs a purely mechanical quantitative injection system that relies entirely on liquid pressure for propulsion. This design fundamentally eliminates the linear drive mechanism required by traditional injection devices, thereby significantly simplifying the device structure, reducing manufacturing costs and maintenance difficulty, while avoiding dependence on external power or gas sources. This significantly improves the reliability and adaptability of the equipment in complex environments such as fields and outdoor areas, achieving low-cost, high-reliability quantitative application of pesticides to plant roots.

[0032] Regarding the specific implementation of the limiting structure 30, as a preferred embodiment, referring to FIG3, the piston 20 is connected to a limiting rod 21. The fixed end (i.e., the bottom end) of the limiting rod 21 is connected to the piston 20, and the free end (i.e., the top end) of the limiting rod 21 passes through the transition cavity 12 and extends to the outside of the piston cavity 10.

[0033] The limiting structure 30 includes a limiting member 31. This limiting member 31 is disposed opposite to the free end of the limiting rod 21. Thus, when the piston 20 drives the limiting rod 21 upward, the free end of the limiting rod 21 will eventually abut against the limiting member 31, thereby limiting the stroke endpoint of the piston 20 as it moves towards the transition chamber 12. Preferably, a buffer pad 32 can be provided on the limiting member 31 for the free end of the limiting rod 21 to abut against, providing cushioning protection.

[0034] Furthermore, embodiments of the present invention further specify that the position of the limiting member 31 in the axial direction of the piston cavity 10 is adjustable.

[0035] It is worth noting that by adjusting the position of the limiting member 31 axially in the piston chamber 10, the upward endpoint of the adjusting piston 20 can be achieved, thereby adjusting the maximum volume of the injection chamber 11, i.e., the single injection volume. This design makes dosage adjustment direct and eliminates the need for complex calibration, enhancing the device's operability and quantitative accuracy. At the same time, its purely mechanical characteristics ensure long-term stable operation in humid and dusty agricultural environments.

[0036] As another preferred embodiment, continuing to refer to FIG3, the limiting member 31 can specifically be a limiting nut.

[0037] In addition, the limiting structure 30 also includes a protective cylinder 33. The protective cylinder 33 is coaxially disposed at the top end of the piston chamber 10.

[0038] The limiting nut, serving as the limiting component 31, is located inside the protective cylinder 33, and its outer wall is threadedly connected to the inner wall of the protective cylinder 33. This allows the limiting nut to move axially along the protective cylinder 33 when rotated, thereby changing its axial position in the piston chamber 10. The protective cylinder 33 provides protection for the limiting nut, reducing the risk of accidental operation.

[0039] In this case, to facilitate the operator's rotation of the limiting member 31, as shown in Figures 3 and 4, the protective cylinder 33 has an operating port 34 extending axially along its wall. The operating port 34 exposes at least a portion of the limiting nut for operation. In other words, the operating port 34 allows the operator to directly rotate the limiting nut from outside the protective cylinder 33, effectively improving the convenience of adjusting the position of the limiting nut.

[0040] In summary, the above-described design not only provides physical protection for the limiting nut 31, extending its service life, but also enables precise and linear adjustment of the piston 20's stroke through the threaded joint. The operating port 34 on the protective cylinder 33 exposes a portion of the limiting nut for operation while simultaneously limiting its movement path, making the adjustment process more stable and controllable. This integrated design compactly positions the limiting structure 30 at the top of the piston chamber 10, optimizing the overall structural layout and enhancing the device's professionalism and durability.

[0041] As another preferred embodiment, continuing to refer to FIG4, the outer wall of the protective cylinder 33 is provided with a scale mark 35 extending along its axial direction. Exemplarily, the scale mark 35 may be a scale line and may be disposed adjacent to the operating port 34; wherein, each scale mark may indicate the volume information corresponding to the injection cavity 11.

[0042] By setting the scale mark 35, the axial position information of the limit nut can be intuitively converted into the volume or injection volume reading of the injection chamber 11, making the dosage setting process visualized and quantified. Operators can quickly and accurately adjust the limit nut to the scale position corresponding to the required dosage without relying on experience or additional tools, which greatly improves work efficiency and dosage consistency, lowers the operation threshold, and provides a simple and easy-to-use technical means for precision agriculture.

[0043] In some possible embodiments, referring to FIG3, the lower surface of the piston 20 is provided with an upwardly recessed buffer cavity 22. The buffer cavity 22 is aligned with both the first channel 14 and the second channel 15. Due to the arrangement of the buffer cavity 22, when the piston 20 descends to its lower limit position where it contacts the bottom of the injection cavity 11, both the first channel 14 and the second channel 15 are in communication with the buffer cavity 22. This design facilitates the smoother entry of the liquid agrochemical in the transition cavity 12 into the injection cavity 11 via the first channel 14 during the metering stage.

[0044] Regarding a specific implementation of the valve assembly 40, as a compact and reliable design, as shown in Figure 3, the first channel 14 and the second channel 15 are arranged sequentially along the radial direction of the injection chamber 11. Exemplarily, both the first channel 14 and the second channel 15 are straight channels extending vertically.

[0045] The valve assembly 40 includes a valve core 41. The valve core 41 passes radially through the first channel 14 and the second channel 15 in sequence along the injection chamber 11. Furthermore, the valve core 41 is provided with a vertically penetrating through-hole 42.

[0046] The valve core 41 is configured to move radially between a first working position and a second working position along the injection chamber 11. When the valve core 41 is in the first working position as shown in Figure 3, the guide port 42 is aligned and connected with the first channel 14, thereby enabling the first channel 14 to be open, while the second channel 15 is closed by the valve core 41 body. When the valve core 41 is in the second working position, the guide port 42 is aligned and connected with the second channel 15, thereby enabling the second channel 15 to be open, while the first channel 14 is closed by the valve core 41 body.

[0047] Through the above configuration, a compact and easy-to-operate slide valve-type channel switching mechanism is constructed. The valve core 41 achieves alignment and connection between the guide port 42 and the first channel 14 or the second channel 15 simply by radial movement, thereby enabling efficient and reliable channel switching. In this design, the valve core 41 has a short stroke, fast response, and low internal flow resistance, ensuring timely and smooth channel switching. Simultaneously, its radial arrangement helps reduce the overall axial dimension of the device.

[0048] As a preferred embodiment, referring to FIG3, the valve assembly 40 further includes an elastic reset member 43 and an operating handle 44 for the reciprocating movement of the valve core 41.

[0049] The resilient reset member 43 is used to resiliently hold the valve core 41 in the first working position. That is, under normal conditions, the resilient reset member 43 can bias the valve core 41 toward the first working position so that it is resiliently held in the first working position. Exemplarily, the resilient reset member 43 may be a straight spring, one end of which is fixed and the other end extends along the direction of movement of the valve core 41 and is connected to the valve core 41.

[0050] An operating handle 44 is disposed on the outer wall of the piston chamber 10 and configured to be operable to apply a driving force to the valve core 41 to move it toward a second working position. Exemplarily, the operating handle 44 may be of a push-button design, with one end of the operating handle 44 hinged to the outer wall of the piston chamber 10 and the other end hinged to the valve core 41.

[0051] Based on the above settings, in the initial state, the valve core 41 is held in the first working position under the action of the elastic reset member 43. Furthermore, when the operator presses the operating handle 44, a driving force is provided to the valve core 41, forcing it to overcome the elastic reset force provided by the elastic reset member 43 and move towards the second working position, thus moving the valve core 41 from the first working position to the second working position. Conversely, when the operator releases the operating handle 44 to remove the driving force, the valve core 41 can automatically reset to the first working position under the action of the elastic reset member 43.

[0052] The above settings enable the "one-button switching and automatic reset" function of valve core 41. The elastic reset element 43 ensures that valve core 41 remains stably in the first working position under normal conditions, preventing accidental opening of the drainage system. This design simplifies the operation process, improves operational safety, and avoids process errors caused by forgetting to switch channels.

[0053] Regarding the specific implementation of the connection between the first channel 14 and the transition cavity 12, as a preferred embodiment, referring to Figures 3 and 4, the first channel 14 is connected to the transition cavity 12 via a connecting pipe 60. This connecting pipe 60 is generally U-shaped and disposed on the outer wall of the piston cavity 10. The operating handle 44 is located within the space formed by the connecting pipe 60 and the outer wall of the piston cavity 10.

[0054] With the above configuration, while ensuring communication between the first channel 14 and the transition cavity 12, the connecting pipe 60 can be used as a protective structure to enclose the operating handle 44, effectively preventing accidental collisions or accidental touches to the operating handle 44 during storage, handling, or operation, thus improving the reliability of the device. At the same time, this layout is compact and aesthetically pleasing, and the U-shaped connecting pipe 60 can also serve as the handheld part of the entire device, improving its practicality.

[0055] Regarding the output section of the entire metering and dispensing device, as shown in Figures 1, 2, and 5, the metering and dispensing device also includes an outlet pipe 50 communicating with the second channel 15. The outlet pipe 50 can be a straight pipe extending vertically, and the distal end (i.e., the bottom end) of the outlet pipe 50 is tapered and sealed. The pipe wall of the outlet pipe 50 is provided with an outlet hole 51 immediately adjacent to its distal end.

[0056] Thus, in actual use of the metering injection device, the distal end of the tapered outlet tube 50 can be easily inserted into the soil until the outlet hole 51 reaches a predetermined position (e.g., a predetermined position near the plant roots). Afterwards, the liquid agrochemical in the injection chamber 11 will enter the outlet tube 50 after being discharged through the second channel 15, and finally flow out from the outlet hole 51, thereby achieving targeted injection of liquid agrochemicals.

[0057] In another preferred embodiment, the liquid outlet pipe 50 has multiple liquid outlet holes 51, which are evenly distributed along the circumference of the liquid outlet pipe 50. Furthermore, each liquid outlet hole 51 extends along the axial direction of the liquid outlet pipe 50.

[0058] The above design allows liquid agrochemicals to flow evenly in all directions, preventing excessive saturation and erosion of localized soil by unilateral discharge. Furthermore, even if some discharge holes 51 are temporarily blocked by soil, the others can still ensure the output of liquid agrochemicals, effectively improving discharge reliability. The axially extending hole shape further reduces the soil pressure on the orifice face, lowering the probability of clogging and ensuring smooth injection operations under various soil conditions.

[0059] As another preferred embodiment, referring to FIG6, the liquid outlet pipe 50 is provided with a one-way valve 52 located upstream of the liquid outlet hole 51.

[0060] The one-way valve 52 is configured to open when the liquid pressure in the injection chamber 11 is higher than a preset value, allowing fluid (i.e., liquid agrochemical) in the outlet pipe 50 to flow to the outlet hole 51, and to close when the liquid pressure in the injection chamber 11 is lower than the preset value, preventing fluid in the outlet pipe 50 from flowing to the outlet hole 51. In other words, liquid agrochemical entering the outlet pipe 50 can only pass through the one-way valve 52 and eventually flow out from the outlet hole 51 when the piston 20 moves downward, causing the liquid pressure in the injection chamber 11 to be higher than a certain preset value; otherwise, liquid agrochemical cannot pass through the one-way valve 52. For example, the one-way valve 52 can be a spring-loaded one-way valve with the valve disc held in the closed position by a spring and having a preset opening pressure; when the liquid pressure of the liquid agrochemical flowing out through the second channel 15 reaches the preset opening pressure of the one-way valve 52, the one-way valve 52 opens to allow the liquid agrochemical to flow through.

[0061] By installing the aforementioned one-way valve 52, automatic leakage of liquid agrochemicals caused by gravity, capillary action, or accidental tilting of the device can be effectively prevented, reducing the risk of waste of liquid agrochemicals during non-operational periods. Simultaneously, it ensures that the injection of liquid agrochemicals is an active and controlled process. This optimized design effectively improves the overall safety and reliability of the device and meets environmental protection requirements.

[0062] As another preferred embodiment, referring to FIG3, a control valve 70 may also be provided between the second channel 15 and the outlet pipe 50. The control valve 70 is used to control the connection or disconnection between the second channel 15 and the outlet pipe 50.

[0063] By using control valve 70, the connection between the outlet pipe 50 and the injection chamber 11 can be independently controlled without disassembling the entire device. The advantages of this design are: First, when cleaning, maintenance, or replacement of the outlet pipe 50 or outlet port 51 is required, the operator can close control valve 70 to isolate the outlet pipe 50 from the piston chamber 10, thus preventing accidental leakage of residual liquid agrochemicals during maintenance and ensuring operational safety and environmental cleanliness. Second, before long-term storage or transportation of the device, closing control valve 70 provides an additional safety guarantee, preventing leakage of liquid agrochemicals due to possible minor leaks in valve assembly 40 or misoperation. Furthermore, in specific operational processes, if injection needs to be temporarily interrupted or different outlet accessories need to be switched, control valve 70 provides a quick and reliable flow path switching method, enhancing the flexibility and functionality of the device.

[0064] In practice, the control valve 70 can be a valve type with a simple structure and reliable sealing, such as a ball valve, plug valve or needle valve.

[0065] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A metering and dispensing device, characterized in that, include: Piston chamber; A piston is axially movable within the piston chamber, dividing the piston chamber into an injection chamber and a transition chamber located above the injection chamber; The transition cavity is provided with an inlet for connecting to an external liquid storage source; the bottom of the injection cavity is provided with a first channel and a second channel that are independent of each other; the first channel is connected to the transition cavity; a limiting structure is provided on one axial side of the piston cavity to limit the stroke of the piston when it moves toward the transition cavity in the axial direction, so as to determine the maximum volume of the injection cavity; A valve assembly for selectively energizing either the first channel or the second channel.

2. The metering and dispensing device according to claim 1, characterized in that, The piston is connected to a limiting rod, the free end of which passes through the transition cavity and extends to the outside of the piston cavity; the limiting structure includes a limiting member; the limiting member is disposed opposite to the free end of the limiting rod, so as to limit the end point of the piston's stroke when it moves toward the transition cavity by the free end of the limiting rod abutting against the limiting member; wherein, the position of the limiting member in the axial direction of the piston cavity is adjustable.

3. The metering and injection device according to claim 2, characterized in that, The limiting component is a limiting nut; the limiting structure also includes a protective cylinder; the protective cylinder is coaxially disposed at the top end of the piston chamber; the limiting nut is disposed inside the protective cylinder and threadedly connected to the protective cylinder; the cylinder wall of the protective cylinder is provided with an operating port extending along its axial direction; the operating port is used to expose at least a portion of the limiting nut for operating the limiting nut to rotate.

4. The metering and injection device according to claim 3, characterized in that, The outer wall of the protective cylinder is marked with graduations.

5. The metering and dispensing device according to claim 1, characterized in that, The first channel and the second channel are arranged sequentially along the radial direction of the injection cavity; the valve assembly includes a valve core; the valve core passes sequentially through the first channel and the second channel along the radial direction of the injection cavity; the valve core is provided with a through port; wherein the valve core is configured to move between a first working position and a second working position along the radial direction of the injection cavity; in the first working position, the through port is aligned and connected with the first channel; in the second working position, the through port is aligned and connected with the second channel.

6. The metering and injection device according to claim 5, characterized in that, The valve assembly further includes a resilient reset member and an operating handle; the resilient reset member is used to resiliently hold the valve core in the first working position; the operating handle is disposed on the outer wall of the piston chamber and is configured to be operable to apply a driving force to the valve core to move toward the second working position.

7. The metering and dispensing device according to claim 6, characterized in that, The first channel is connected to the transition cavity through a connecting pipe; the connecting pipe is U-shaped and disposed on the outer wall of the piston cavity; the operating handle is located within the space formed by the connecting pipe and the outer wall of the piston cavity.

8. The metering and dispensing device according to claim 1, characterized in that, It also includes a liquid outlet pipe that communicates with the second channel; the distal end of the liquid outlet pipe is conical and sealed; and the wall of the liquid outlet pipe is provided with a liquid outlet hole adjacent to its distal end.

9. The metering and dispensing device according to claim 8, characterized in that, There are multiple liquid outlet holes, which are evenly distributed along the circumference of the liquid outlet pipe; each liquid outlet hole extends along the axial direction of the liquid outlet pipe.

10. The metering and dispensing device according to claim 8, characterized in that, The liquid outlet tube is provided with a one-way valve located upstream of the liquid outlet hole; the one-way valve is configured to open when the liquid pressure in the injection chamber is higher than a preset value, so as to allow the fluid in the liquid outlet tube to flow to the liquid outlet hole.

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