Liquid injection valve

Abstract

The application relates to the technical field of liquid injection, in particular to a liquid injection valve. The liquid injection valve comprises a valve body, a valve core and a spring. The valve core is arranged in the valve body and forms a liquid flow channel with the valve body. The channel comprises first, second and third channel segments arranged in sequence along the flow direction and having stepped changes in flow cross-sectional area. The valve body and the valve core of the injection end are respectively provided with gradually expanding openings and gradually expanding ends matched with each other, and the injection end is provided with a liquid injection opening communicated with the channel. The spring provides a pre-tightening force to keep the valve core closed. During operation, the liquid pressure pushes the valve core to move axially to overcome the spring force and open the injection. The structure optimizes the fluid state through the multi-segment variable-diameter flow channel design, can effectively prevent the melt backflow, significantly improves the additive dispersion uniformity and injection stability, and can accurately control the injection amount by adjusting the valve core stroke.

Description

Technical Field

[0001] This application relates to the field of liquid injection technology, and specifically to a liquid injection valve. Background Technology

[0002] In the extrusion process of engineering plastics, the precise injection of liquid additives into the molten material is a crucial step in achieving product performance. Traditional injection units often employ a syringe-like extrusion structure, relying on external thrust to force liquid into the extruder barrel. However, the extruder typically maintains a high-pressure environment. When the injection pressure at the injection valve is insufficient or fluctuates, the high-temperature molten material inside the barrel can easily flow backward into the valve body along the injection channel. This melt backflow phenomenon not only rapidly clogs the valve body flow channel, preventing the additive from being injected properly, but also affects the valve core's movement accuracy due to solidified residues, ultimately leading to unstable product quality or even batch scrap.

[0003] Furthermore, existing injection valves have significant limitations in terms of liquid dispersion uniformity. Conventional designs often employ simple through-hole or fixed-slit structures, allowing liquid additives to enter the high-viscosity melt in a single jet, making it difficult to achieve sufficient diffusion and mixing within a short time. This localized concentration unevenness can easily lead to defects in the final product, such as color differences, performance fluctuations, or decreased mechanical strength. Especially for the production of high-precision engineering plastics, insufficient dispersion directly affects the material's thermal stability, mechanical properties, and batch consistency, becoming a major bottleneck restricting product quality improvement.

[0004] Therefore, developing an injection valve structure that can actively block melt backflow and optimize additive dispersion has become a key technical challenge that the industry urgently needs to overcome. Utility Model Content

[0005] In view of the above problems, this application provides a liquid injection valve, comprising:

[0006] The valve body has an internal receiving space; and

[0007] The valve core is disposed in the receiving space of the valve body and forms a liquid flow channel with the valve body;

[0008] The liquid injection valve has an injection end and an injection end at its two ends. The valve body port at the injection end has a gradually expanding opening that gradually narrows towards the inside of the valve body. The corresponding end of the valve core has a gradually expanding end that cooperates with the gradually expanding opening. The cooperation between the gradually expanding end and the gradually expanding opening constitutes a sealing pair for opening and closing the injection end.

[0009] The injection end is provided with a liquid injection opening that communicates with the liquid flow channel;

[0010] A spring is provided between the valve core and the valve body so that the valve core can move axially back and forth inside the valve body, thereby realizing the start and stop of the liquid injection valve injection action.

[0011] Optionally, the liquid flow channel includes a first channel segment, a second channel segment, a third channel segment, and an injection segment formed sequentially along the liquid flow direction; the flow cross-sectional area of ​​the second channel segment is larger than that of the first channel segment, and the flow cross-sectional area of ​​the third channel segment is smaller than that of the second channel segment but larger than that of the first channel segment; the injection end is formed by the gradually expanding end and the gradually mating end.

[0012] Optionally, the spring is in a pre-compressed state, and the pre-pressure it provides causes the expanding end to press tightly against the expanding opening when no liquid is injected, thereby achieving self-sealing of the liquid injection valve.

[0013] Optionally, at least two centrally symmetrical planes are machined along the axial direction on the outer ring of the valve core, and the space between the planes and the inner wall of the valve body forms the liquid flow channel.

[0014] Optionally, the injection end is further provided with a connecting joint, which is covered and sleeved on one end of the valve body, and has an internal accommodating space and a liquid receiving port; the connecting joint and the valve body are sealed by a first gasket.

[0015] Optionally, a nut is fixed to the end of the valve core inside the connecting joint, and a second washer is provided close to the nut. One end of the spring abuts against the second washer, and the other end abuts against the inner wall of the valve body.

[0016] Optionally, a valve sleeve is also provided at the injection end, the valve sleeve is sleeved around the spring, and the liquid injection opening is provided on its side wall; a valve core movement reserve gap is left between the second gasket and the valve sleeve to limit the maximum movement distance of the valve core.

[0017] The technical effects achieved by the above-mentioned technical solution in this application are as follows:

[0018] The liquid injection valve technology solution provided in this application significantly improves the reliability and effectiveness of injecting liquid additives under high-pressure extrusion environments through its unique structural design. Its core beneficial effects are reflected in three main aspects: active anti-backflow, optimized dispersion, and operational controllability.

[0019] This valve employs a combination of spring preload and conical sealing surface design. In the non-operating state, the spring force ensures a tight seal between the valve core and the valve body, forming a reliable self-sealing structure. This mechanism effectively resists the backflow impact of high-pressure molten material inside the extruder barrel, fundamentally preventing melt backflow, avoiding flow channel blockage and valve core jamming problems, and greatly improving the valve's operational stability and service life.

[0020] In terms of fluid channel design, this valve employs a multi-stage variable diameter structure. The fluid sequentially passes through the first, second, and third channel sections, each with a progressively changing cross-sectional area, undergoing acceleration, diffusion, and then moderate contraction. This stepped change not only utilizes the high-speed flow in the first section to establish a dynamic pressure barrier preventing backflow, but also achieves velocity reduction and pressure homogenization through channel expansion in the second section, promoting initial fluid mixing. Finally, the fluid is ejected in a uniform and stable radial atomization pattern in the third and injection sections, significantly improving the dispersion uniformity and mixing efficiency of additives in high-viscosity melts, thereby ensuring the consistency of the final product's performance and quality stability.

[0021] Furthermore, this technical solution boasts excellent adjustability. By changing the thickness of the second gasket or adjusting the position of the nut, the maximum travel of the valve core can be precisely controlled, thereby fine-tuning the liquid outlet gap and instantaneous flow rate at the injection end. This design allows the same valve body to adapt to different process requirements and injection volumes, enhancing the versatility of the equipment and production flexibility. The entire valve body has a compact structure, with precision fits and multiple sealing designs between components, ensuring long-term operational accuracy and sealing reliability under high-frequency start-stop and high-pressure conditions, providing key process assurance for the high-quality preparation of engineering plastics. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the present application and form part of the specification. They are used together with the embodiments of the present application to explain the application and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic cross-sectional view of the structure of a liquid injection valve provided in some embodiments of this application;

[0024] Figure 2 for Figure 1 A sectional view along AA in the diagram;

[0025] Figure 3 A schematic cross-sectional view of the injection end of a liquid injection valve in a closed state, provided in some embodiments of this application;

[0026] Figure 4 This is a schematic cross-sectional view of the ejection end of a liquid injection valve in the injection state, provided in some embodiments of this application.

[0027] Figure label:

[0028] 1. Valve body; 11. Gradually expanding opening; 2. Valve core; 21. Gradually expanding end; 3. Spring; 4. Valve sleeve; 41. Liquid injection opening; 5. Connecting joint; 51. Liquid receiving port; 6. Nut; 7. First gasket; 8. Second gasket; 9-1. Injection end; 9-2. Injection end; 10. Liquid flow channel; 10-1. First channel section; 10-2. Second channel section; 10-3. Third channel section; 10-4. Injection section. Detailed Implementation

[0029] In the following description, only certain exemplary embodiments are depicted simply. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this application. Therefore, the drawings and description are considered exemplary in nature and not restrictive.

[0030] Unless otherwise defined herein, scientific and technical terms used in conjunction with this application will have the meanings commonly understood by one of ordinary skill in the art. Furthermore, unless the context otherwise requires, singular terms shall include plural forms, and plural terms shall include singular forms. More specifically, as used in this specification and the appended claims, unless the context explicitly indicates otherwise, the singular forms “a,” “an,” and “the” include plural indicators. In this application, unless otherwise stated, the use of “or” means “and / or.” Furthermore, the use of the term “comprising” and other forms such as “including” and “containing” is not limiting. Moreover, the scope provided in the specification and the appended claims includes all values ​​between endpoints. Preferred embodiments of this application are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of this application.

[0031] See Figures 1 to 4 This application provides a liquid injection valve, which is cylindrical in shape and mainly composed of a valve body 1, a valve core 2, a spring 3, a valve sleeve 4, a connecting joint 5, a nut 6, a first gasket 7, and a second gasket 8, to achieve precise injection of liquid additives and prevent backflow. The specific implementation method is described in detail below with reference to structural details and working principle:

[0032] The liquid injection valve has two ends, namely the injection end 9-1 (the end connected to the liquid supply system) and the injection end 9-2 (the end that sprays liquid).

[0033] At the injection end 9-1, a connecting connector 5 is fitted over one end of the valve body 1, forming a receiving space within it. The connecting connector 5 has a liquid receiving port 51 that can connect to an external liquid supply device, allowing liquid to enter the liquid injection valve. A first gasket 7 is provided between the connecting connector 5 and the valve body 1. When the connecting connector 5 is tightened, the first gasket 7 is compressed, filling the gap between them and completely preventing liquid leakage.

[0034] The valve body 1 is the main support component of the liquid injection valve. It is a hollow cylinder with an axially penetrating interior space.

[0035] The valve core 2 is reciprocally movable within the receiving space of the valve body 1. At least two centrally symmetrical planes are machined axially on its outer ring, forming a liquid flow channel 10 between the planes and the inner wall of the valve body's receiving space. This channel is the path for liquid to flow from the injection end 9-1 to the injection end 9-2. The symmetrical design prevents liquid deviation. Furthermore, the outer ring of the valve core 2 and the inner wall of the valve body 1's receiving space are fitted with a zero-clearance fit (clearance ≤ 0.01 mm) to prevent the valve core 2 from shaking or deforming during reciprocating movement, ensuring the stability of sealing and injection.

[0036] In some embodiments, such as Figure 2 As shown, four centrally symmetrical planes are machined along the axial direction on the outer ring of the valve core 2, and liquid flow channels 10 are formed between the planes and the inner wall of the valve body accommodating space.

[0037] One end of the valve core 2 extends out of the valve body 1 and is located within the receiving space formed in the connecting joint 5. This end of the valve core 2 is provided with a nut 6, a second washer 8, a valve sleeve 4, and a spring 3. The nut 6 is threadedly fixed to the leftmost end of the valve core 2 (at...). Figure 1 (For example). The second gasket 8 is fitted onto the valve core 2 and is located at the right end of the second gasket 8, fitting snugly against it. One end of the spring 3 abuts against the second gasket 8, and the other end rests against the inner wall of the valve body 1. The spring 3 is in a pre-compressed state during assembly (the pre-compression amount is adjusted according to the working pressure of the liquid injection valve in the liquid injection scenario), and its elastic force always pushes the valve core 2 away from the injection end 9-2, keeping the injection end 9-2 closed, thus realizing the normally closed structure of the liquid injection valve. The valve sleeve 4 is fitted around the spring 3, forming an extension of the accommodating space of the valve body 1. Multiple liquid injection openings 41 are provided on the side wall of the valve sleeve 4, which are connected to the liquid flow channel 10—the liquid enters the accommodating space in the connecting joint 5 through the liquid receiving port 51, then enters the liquid flow channel 10 through the liquid injection openings 41, and finally flows to the injection end 9-2.

[0038] The valve body 1 at the port of the injection end 9-2 is machined to form a gradually expanding opening 11—that is, a conical surface that gradually narrows from the port towards the interior of the valve body. The valve core 2 at the end of the injection end 9-2 is machined to form a gradually expanding end 21 (conical tail end), the taper of which perfectly matches the taper of the gradually expanding opening 11 of the valve body. The fit between the gradually expanding end 21 and the gradually expanding opening 11 constitutes a sealing pair for opening and closing the injection end 9-2.

[0039] In the initial state, the diffuser end 21 is fitted with the diffuser opening 11 to seal the injection end 9-2. During injection, the liquid pushes the valve core 2 to the right, the spring 3 is further compressed, and the liquid is injected from between the diffuser end 21 and the diffuser opening 11.

[0040] In some embodiments, a valve core movement clearance is provided between the second gasket 8 and the valve sleeve 4. The width of this clearance can be adjusted according to process requirements. Adjustment can be achieved by increasing or decreasing the thickness of the second gasket 8 or by moving the nut 6. The function of the valve core movement clearance is to adjust the distance the valve core 2 delves into the valve body 1: decreasing the width of the valve core movement clearance reduces the depth of the valve core 2, resulting in a smaller liquid outlet gap at the injection end 9-2 (i.e., the conical gap between the expanding end and the expanding opening); increasing the width of the valve core movement clearance increases the depth of the valve core 2, resulting in a larger liquid outlet gap at the injection end 9-2 (i.e., the conical gap between the expanding end and the expanding opening). By adjusting the width of the valve core movement clearance, the maximum movement distance of the valve core can be precisely controlled, thereby achieving adjustment of the injection volume.

[0041] In some embodiments, the liquid flow channel 10 adopts a multi-segment variable diameter design, specifically including a first channel segment 10-1, a second channel segment 10-2, a third channel segment 10-3, and an injection segment 10-4 arranged sequentially along the liquid flow direction.

[0042] The inner diameter of the first channel section 10-1 is relatively small, and its diameter can be adjusted according to the actual fluid viscosity and flow rate requirements to create a higher initial flow velocity and enhance fluid kinetic energy. The inner diameter of the second channel section 10-2 is significantly larger than that of the first section. The sudden expansion of this channel section allows the fluid to enter the buffer diffusion zone, reducing the flow velocity and restoring static pressure. This helps to eliminate flow eddies and initially homogenize the fluid pressure distribution, moderately constricting the fluid and stabilizing the flow state, providing uniform fluid conditions for subsequent injection. The inner diameter of the third channel section 10-3 is smaller than that of the second channel section 10-2 but larger than that of the first channel section 10-1, increasing the flow velocity so that the liquid is ejected in a uniform radial pattern, increasing the injection force. The injection section 10-4, which is the conical gap between the gradually expanding end 21 and the gradually expanding opening 11, allows the liquid to be sprayed out in all directions. The size of the injection section 10-4 is adjusted by adjusting the valve core movement clearance to obtain different injection speeds.

[0043] This stepped variable diameter structure achieves multiple technical effects through a fluid dynamics design of "contraction-expansion-recontraction": First, the higher flow rate in the first stage can effectively prevent melt backflow, especially in the early stage of injection, to establish a sufficient dynamic pressure barrier; Second, the expansion zone in the second stage allows the additive fluid to have sufficient space for turbulent mixing, avoiding component separation caused by excessive flow rate, and enabling the fluid to form a stable laminar flow before the outlet; Third, the contraction in the third and fourth stages makes the liquid present a uniform radial atomization pattern when it is sprayed out.

[0044] This multi-channel structure together constitutes an efficient and stable fluid delivery and injection system, which is particularly suitable for the precise injection and dispersion of high-viscosity additives under high-pressure extrusion conditions.

[0045] The working process of the liquid injection valve provided in this application is as follows:

[0046] In the initial state, spring 3 is in a pre-compressed state, and its elastic force pushes valve core 2 towards the injection end 9-1, so that the gradually expanding end 21 of valve core 2 tightly fits against the gradually expanding opening 11 of valve body 1, thereby achieving a seal at the injection end 9-2, and the liquid injection valve is in a normally closed state. When the external liquid supply system injects liquid into the valve through the liquid receiving port 51 of the connecting joint 5, the liquid first enters the receiving space inside the connecting joint 5, and then enters the liquid flow channel 10 formed between the multiple centrally symmetrical planes of the outer ring of valve core 2 and the inner wall of valve body 1 through the multiple liquid injection openings 41 on the side wall of valve sleeve 4. As the liquid pressure gradually increases, the hydraulic pressure acts on the end face of valve core 2, overcoming the pre-pressure of spring 3, and pushing valve core 2 to move axially towards the injection end 9-2. The movement of valve core 2 further compresses spring 3, and causes the gradually expanding end 21 to gradually disengage from the gradually expanding opening 11, forming a conical gap, namely the injection section 10-4. The liquid flows sequentially through the first channel section 10-1, the second channel section 10-2, and the third channel section 10-3, and is finally ejected radially through the injection section 10-4. The first channel section 10-1 has a smaller inner diameter to increase flow velocity, enhance fluid kinetic energy, and prevent melt backflow. The second channel section 10-2 has a larger inner diameter, serving to buffer diffusion, stabilize the flow pattern, and homogenize pressure. The third channel section 10-3 has an inner diameter between the two, used to moderately increase flow velocity and ensure the liquid is ejected in a uniform atomized form. Throughout the injection process, the movement distance of the valve core 2 is limited by the pre-reserved gap in the valve core movement. This gap can be precisely controlled by adjusting the thickness of the second shim 8 or the position of the nut 6, thereby regulating the injection volume and spray speed. When the injection ends and the liquid pressure decreases, the spring force of the spring 3 pushes the valve core 2 back to reset, causing the gradually expanding end 21 to re-fit with the gradually expanding opening 11, closing the injection end 9-2, and completing one injection cycle.

[0047] Finally, it should be noted that the above descriptions are merely preferred embodiments of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A liquid injection valve, characterized in that, include: The valve body has an internal accommodating space. and The valve core is disposed in the receiving space of the valve body and forms a liquid flow channel with the valve body; The liquid injection valve has an injection end and an injection end at its two ends. The valve body port at the injection end has a gradually expanding opening that gradually narrows towards the inside of the valve body. The corresponding end of the valve core has a gradually expanding end that cooperates with the gradually expanding opening. The cooperation between the gradually expanding end and the gradually expanding opening constitutes a sealing pair for opening and closing the injection end. The injection end is provided with a liquid injection opening that communicates with the liquid flow channel; A spring is provided between the valve core and the valve body so that the valve core can move axially back and forth inside the valve body, thereby realizing the start and stop of the liquid injection valve injection action.

2. The liquid injection valve according to claim 1, characterized in that, The liquid flow channel includes a first channel segment, a second channel segment, a third channel segment, and an injection segment formed sequentially along the liquid flow direction; the flow cross-sectional area of ​​the second channel segment is larger than that of the first channel segment, and the flow cross-sectional area of ​​the third channel segment is smaller than that of the second channel segment but larger than that of the first channel segment; the injection segment is formed by the cooperation of the gradually expanding end and the gradually expanding opening.

3. The liquid injection valve according to claim 1, characterized in that, The spring is in a pre-compressed state, and the pre-pressure it provides causes the expanding end to press tightly against the expanding opening when no liquid is injected, thereby achieving the self-sealing of the liquid injection valve.

4. The liquid injection valve according to claim 1, characterized in that, At least two centrally symmetrical planes are machined along the axial direction on the outer ring of the valve core, and the space between the planes and the inner wall of the valve body forms the liquid flow channel.

5. The liquid injection valve according to claim 1, characterized in that, The injection end is also provided with a connecting joint, which is covered and sleeved on one end of the valve body. It has an internal receiving space and a liquid receiving port. The connecting joint and the valve body are sealed by a first gasket.

6. The liquid injection valve according to claim 5, characterized in that, A nut is fixed to the end of the valve core inside the connector, and a second washer is provided close to the nut. One end of the spring abuts against the second washer, and the other end abuts against the inner wall of the valve body.

7. The liquid injection valve according to claim 6, characterized in that, A valve sleeve is also provided at the injection end. The valve sleeve is fitted around the spring, and the liquid injection opening is provided on its side wall. A valve core movement reserve gap is left between the second gasket and the valve sleeve to limit the maximum movement distance of the valve core.

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