A gun needle valve assembly and spray gun

Abstract

The utility model relates to a spraying equipment technical field especially relates to a gun needle valve assembly and application this assembly's spray gun, gun needle valve assembly, include: the seat body, its front end is provided with the valve element mounting seat for installing ball head valve element, the opening diameter of valve element mounting seat end part is less than the diameter of ball head valve element, the gun needle bar is worn and is established in the seat body, one end of gun needle bar is provided with the limit step, ball head valve element, wherein, gun needle bar, seat body and ball head valve element jointly constitute the gun needle assembly, the utility model provides a kind of gun needle valve assembly and the spray gun using it, solve the technical problem that the precision of gun needle in prior art is low, short life, poor reliability, and valve assembly overall disassembly is inconvenient, quick-release structure connection is unreliable.

Description

Technical Field

[0001] This utility model relates to the field of spraying equipment technology, and in particular to a needle valve assembly for a high-pressure airless spray gun, which has a non-welded precision structure and can be quickly disassembled and assembled, and a spray gun using the assembly. Background Technology

[0002] As a core piece of equipment in the modern coating industry, the performance of high-pressure airless spray guns directly affects the efficiency, quality, and cost of coating operations. Among the many components of the spray gun, the needle valve assembly plays a crucial role. It is responsible for precisely controlling the opening and closing of the paint channel under high pressure. The reliability of its structure, the accuracy of its operation, and the ease of maintenance are key factors in evaluating the performance of a professional-grade spray gun.

[0003] Existing spray gun technology still suffers from some technical problems in the design and manufacturing process of its needle valve assembly. These problems not only limit the further improvement of spray gun performance, but also bring a lot of inconvenience to front-line operators.

[0004] Firstly, in the manufacturing of the core moving component, the spray gun needle, traditional processes generally employ welding to connect the slender needle rod to the ball valve core at the front end. However, the localized high temperatures during welding inevitably generate thermal stress on the needle rod. After cooling, this stress easily leads to bending or twisting deformations that are difficult to detect with the naked eye, thereby compromising its critical straightness and coaxiality. During the high-frequency reciprocating motion of the spray gun, this precision defect causes uneven, one-sided, and severe wear on the mating seal, resulting in premature seal failure and paint leakage. The lifespan of the seal is often only a fraction of that under ideal conditions, leading to frequent downtime for seal replacement. This not only directly increases spare parts and maintenance costs but, more seriously, reduces the continuity of construction and overall efficiency. In addition, the weld point itself is a weak link in the metallographic structure, forming a stress concentration point; when the spray gun is working, the high-pressure coating will generate huge pulse impact force on the valve core, which can reach thousands of times per minute. This impact force will be transmitted along the needle rod; over time, the weld point is very prone to microcracks due to metal fatigue, which will eventually lead to brittle fracture, causing the needle to be scrapped suddenly and the construction to be interrupted unexpectedly.

[0005] Secondly, to avoid the drawbacks of welding, other connection methods for the gun needles have emerged in the industry. For example, the gun needle rod is screwed to the valve core using threads and then secured with anaerobic adhesive. However, this method still has long-term reliability issues in the face of the strong vibrations and huge impacts of the spray gun. The threads are at risk of loosening, and the adhesive layer may fail due to aging or solvent corrosion. Utility Model Content

[0006] The purpose of this utility model is to provide a gun needle valve assembly and a spray gun using it, aiming to systematically solve the technical problems in the prior art, such as low precision, short life and poor reliability of the gun needle due to welding or simple assembly, as well as the inconvenience of overall disassembly and assembly of the valve assembly and the unreliability of the quick-release structure connection.

[0007] To achieve the above objectives, the core technical solution adopted by this utility model is as follows: a needle valve assembly, comprising: The seat has a valve core mounting seat at its front end for mounting the ball valve core, and the opening diameter at the end of the valve core mounting seat is smaller than the diameter of the ball valve core. The needle bar is inserted into the seat body, and a limit step is provided at one end of the needle bar; Ball head valve core; The needle assembly consists of the needle rod, the seat, and the ball valve core.

[0008] Furthermore, the ball valve core and the valve core mounting seat are connected by extrusion or riveting.

[0009] Furthermore, it also includes: a connecting sleeve, to which the end of the needle assembly is connected; The seal, passed through the needle rod, is located between the base and the connecting sleeve; An internal preload spring, located between the seal and the seat, applies axial preload to the needle assembly to eliminate clearance between the needle rod and the seat.

[0010] Furthermore, the seal has an outer stepped surface, and the connecting sleeve has an inner stepped surface that abuts against the outer stepped surface. The outer stepped surface and the inner stepped surface cooperate to achieve axial positioning of the seal within the connecting sleeve.

[0011] Furthermore, the needle assembly is fixed to the connecting sleeve by at least two opposing set screws. The set screws are arranged radially along the connecting sleeve, and the end of the needle rod is provided with a set groove, in which the set screw can be engaged.

[0012] Furthermore, the connecting sleeve is provided with a transverse pin through hole that extends radially through it; the connecting sleeve is also provided with a locking component mounting hole that opens axially along it, the side wall of the locking component mounting hole is connected to the transverse pin through hole, and the locking component mounting hole is provided with an elastic locking component for elastically engaging with the transverse pin inserted into the transverse pin through hole.

[0013] Furthermore, the locking assembly mounting hole has an internal thread at the end away from the seal; the resilient locking assembly includes a steel ball and a pin-locking spring, and the preload of the pin-locking spring on the steel ball can be adjusted by the depth of the adjusting screw screw screwed into the internal thread.

[0014] Furthermore, the middle of the lateral pin has a positioning groove for engaging with the steel ball of the elastic locking assembly.

[0015] Furthermore, the cross-section of the positioning groove is shaped like a triangle.

[0016] Furthermore, a spray gun is also provided, which includes: The spray gun body has a cavity and a movable handle. The movable handle is rotatably connected to the cavity shown. The outlet of the cavity is equipped with a threaded sealing cap, and the sealing cap is provided with a discharge hole; This also includes the needle valve assembly mentioned above; The needle valve assembly is located inside the cavity, and a sealing spring is installed between the cavity and the needle valve assembly. The sealing spring can press the ball valve core against the discharge hole to seal the cavity. The movable handle is connected to the connecting sleeve of the needle valve assembly through a transverse pin. When the movable handle is rotated, it can squeeze the sealing spring, drive the needle valve assembly to move in the cavity, and thus disengage the ball valve core from the discharge hole.

[0017] Beneficial effects: 1. Improved Precision and Lifespan: The needle assembly of this invention employs a non-welded, permanent mechanical connection. Through a unique structural design—specifically, the tapered structure at the end of the valve core mounting seat—the ball-head valve core is permanently and precisely secured. This cold-working mechanical method physically reduces thermal deformation caused by high welding temperatures, ensuring coaxiality and straightness between the needle rod and the ball-head valve core. The high-precision needle exhibits extremely uniform and minimal wear on the seals during reciprocating motion, extending their lifespan and reducing maintenance costs and downtime for users. Simultaneously, the internal preload spring further enhances the reliability of the non-welded structure. By applying continuous axial preload, it eliminates any minute gaps that may exist between mechanical components, improving the needle assembly's stability and enabling it to withstand long-term, high-frequency impacts and vibrations, thus increasing the needle's durability and lifespan.

[0018] 2. Improved Reliability and Stability: The non-welded mechanical connection method results in a complete structure without the stress concentration weaknesses found in welded joints. This allows the needle assembly to better distribute and withstand the impact forces from high-pressure fluids, improving its fatigue fracture resistance compared to welded components. The internal preload spring design enhances the long-term stability of this mechanical assembly. In the preferred design, opposing set screws engage with the set grooves on the needle rod, achieving dual axial and circumferential locking and reducing the possibility of other relative movements. For external connections, the quick-release self-locking mechanism uses adjustable preload steel balls to elastically lock the pin, improving connection stability, reducing the risk of accidental pin slippage during severe vibrations, and ensuring operational safety.

[0019] 3. Improved maintenance convenience: This utility model allows for tool-free quick disassembly and assembly from the spray gun body via a single horizontal pin. When users need to clean, inspect, or replace the valve core or seals, they do not need to carry or search for any special tools; they can complete disassembly and reassembly by hand in a short time, improving maintenance efficiency and reducing time costs caused by maintenance.

[0020] 4. Adjustable and Maintainable Design: The quick-release self-locking mechanism in this design does not have a fixed locking force from the core steel ball; instead, it can be precisely and quantitatively adjusted via an external adjusting screw. This means that when normal wear occurs on the pin or hole wall due to long-term use, the user does not need to replace the entire assembly. Simply tightening the adjusting screw compensates for the wear clearance, restoring the initial locking effect. This design extends the product's lifespan and reduces the user's long-term ownership costs. Attached Figure Description

[0021] To enable those skilled in the art to more clearly and comprehensively understand the technical solution of this utility model, the preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be noted that the accompanying drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of a needle valve assembly provided in an embodiment of the present invention.

[0022] Figure 2 This is an exploded schematic diagram of a spray gun structure provided in an embodiment of this utility model.

[0023] In the above figures, the same reference numerals denote parts that have the same or similar functions. The names of the parts represented by each reference numeral are as follows: 1-Connecting sleeve; 11-Inner stepped surface; 12-Transverse pin through hole; 13-Locking component mounting hole; 14-Internal thread; 2-Seal; 21-Outer step surface; 3-Needle assembly; 31-Seal; 32-Needle rod; 321-Limit step; 322-Fixing groove; 33-Ball valve core; 4-Internal preload spring; 5-Set screw; 6-Elastic locking assembly; 61-Steel ball; 62-Pin engaging spring; 63-Adjusting screw; 7- Lateral pin; 71- Positioning groove; 8-Spray gun body; 81-Cavity; 82-Modible handle; 9-Sealing cap; 91-Discharge hole; 10 - Sealed spring. Detailed Implementation

[0024] The present invention will now be described in detail with reference to the accompanying drawings: To make the objectives, technical solutions, and advantages of this utility model clearer, several preferred embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the embodiments described herein are merely for explaining this utility model and do not constitute any limitation on its scope of protection. Any modifications, equivalent substitutions, or improvements made based on the spirit and principles of this utility model should be included within the scope of protection of this utility model.

[0025] Example Please refer to this document. Figures 1 to 2 This specific embodiment provides a needle valve assembly for a spray gun. In this embodiment, the needle valve assembly includes a core needle assembly 3. The needle assembly 3 consists of a seat 31, a needle rod 32 passing through the seat 31, and a ball valve core 33. One end of the needle rod is also provided with a limiting step. The core innovation of its structure lies in the fact that the front end of the seat 31 is provided with a valve core mounting seat for mounting the ball valve core 33. The valve core mounting seat is specially designed so that the opening diameter at its end is smaller than the diameter of the ball valve core 33, and due to the setting of the limiting step, the needle rod can no longer pass out of the seat. This structural feature is the key physical basis for achieving a non-welded permanent connection. This means that once the ball valve core 33 is placed inside the valve core mounting seat, it will be physically restricted axially by the smaller opening, preventing it from detaching from the front end. This fundamentally eliminates the need for traditional welding processes, completely avoiding the risk of thermal deformation of the needle rod 32 due to localized high temperatures during welding. It ensures that the axis of the needle rod 32 and the center of the ball valve core 33 maintain extremely high coaxiality. This high precision guarantees the sealing performance of the spray gun and extends the life of the seals.

[0026] As a preferred embodiment capable of achieving the aforementioned permanent fixing structure, the ball valve core 33 is connected to the valve core mounting seat by extrusion or riveting. Specifically, during the manufacturing process, in the initial stage of forming, the inner diameter of the end opening of the valve core mounting seat is slightly larger than the diameter of the ball valve core 33, so as to facilitate the smooth insertion of the ball valve core 33 (typically a high-hardness, high-precision steel ball). After the ball valve core 33 and the needle rod 32 are assembled in place, a huge, precisely controlled radial pressure is applied to the edge of the end opening of the valve core mounting seat using a dedicated extrusion or riveting die, causing the material to undergo permanent plastic deformation, flow inward and close, and the final opening diameter is smaller than the diameter of the ball valve core 33, thereby firmly and permanently wrapping and fixing the ball valve core 33. The entire fixing process is carried out at room temperature without heat input (such as welding), thus reducing the negative impact on the dimensional accuracy of the components, the metallographic structure of the material, and the mechanical properties, ensuring that each needle assembly 3 leaving the factory has a high degree of consistency in process and performance.

[0027] Furthermore, to integrate this core needle assembly 3 into a complete functional module, the needle valve assembly of this embodiment also includes a connecting sleeve 1, the end of the needle assembly 3 being connected to the connecting sleeve 1; a sealing element 2, which is passed through the needle rod 32 and disposed between the seat 31 and the connecting sleeve 1, and generally has a rubber or silicone sealing ring on its outer periphery; and an internal preload spring 4. The internal preload spring 4 is disposed between the sealing element 2 and the seat 31 of the needle assembly 3. The core function of the internal preload spring 4 is not to provide the main motion return force of the needle assembly 3 during operation, but rather as an internal clearance compensation and dynamic stabilization mechanism. After the assembly is assembled, the spring 4 is always in a certain compressed state, applying a continuous axial preload force pointing towards the rear end of the connecting sleeve 1 to the seat 31 through the sealing element 2 as a support base for the reaction force. This preload ensures that the limiting step 321 of the needle rod 32 and the mating step surface inside the seat 31 maintain a high-pressure, tight fit. The innovation of this design lies in the applicant's awareness of the potential risk of slight loosening in the non-welded mechanical assembly (needle rod 32 and seat 31) under long-term high-frequency vibration. By applying this continuous preload, the axial clearance that may exist between the two due to machining tolerances is completely eliminated, making the assembly more stable. The connecting sleeve 1 is preferably made of brass, as it has good machinability, excellent corrosion resistance, and a certain degree of self-lubrication, making it very suitable as a valve body part. The sealing element 2 can be equipped with one or more O-rings made of fluororubber or perfluoroether rubber as needed to accommodate different types of paint solvents.

[0028] To ensure a precise and repeatable installation position of all internal components within the connecting sleeve 1, the seal 2 has an outer stepped surface 21. Correspondingly, the inner bore of the connecting sleeve 1 is machined with an inner stepped surface 11 that matches and tightly abuts against the outer stepped surface 21. The engagement of the outer stepped surface 21 and the inner stepped surface 11 enables precise axial positioning of the seal 2 within the connecting sleeve 1. This flange-like contact positioning method offers higher positioning accuracy and stability compared to positioning via thread depth or pin holes. It provides a fixed axial reference plane for the entire needle valve assembly, ensuring high consistency regardless of replacement or reinstallation, and guaranteeing stable coating results.

[0029] To securely and precisely fix the needle assembly 3 within the connecting sleeve 1, the needle assembly 3 is secured to the connecting sleeve 1 using at least two opposing set screws 5. Specifically, two threaded holes radially distributed at 180 degrees are formed on the side wall of the connecting sleeve 1. Correspondingly, a set groove 322 is provided at the end of the needle rod 32. This set groove 322 can be an annular groove or two dot-shaped recesses corresponding to the screw positions. By symmetrically screwing in two set screws 5 (e.g., headless hexagonal head screws or flat-end screws) from both sides, their ends can be locked within the set groove 322. This design offers the following advantages: First, the two opposing screws apply a completely balanced locking force without any lateral component. Compared to traditional single-screw locking, this effectively avoids the problem of the needle assembly 3 deflecting or deviating from the central axis within the sleeve due to unidirectional locking force, thus maximizing its installation coaxiality. Second, the engagement between the screw end and the locking groove 322 not only provides a strong radial locking force but also provides reliable axial and circumferential (anti-rotation) locking, reducing the probability of any form of relative movement of the needle assembly 3 within the connecting sleeve 1.

[0030] Another innovation of this utility model lies in its connection method with the spray gun body. Specifically, the connecting sleeve 1 is provided with a transverse pin through hole 12 extending radially through it. Simultaneously, the connecting sleeve 1 is also provided with a locking component mounting hole 13 opening axially. The inner sidewall of the locking component mounting hole 13 is interconnected with the transverse pin through hole 12, forming a "T"-shaped internal channel structure. Furthermore, an elastic locking component 6 is pre-installed within the locking component mounting hole 13. The function of the elastic locking component 6 is to reliably and elastically engage with the transverse pin 7 subsequently inserted into the transverse pin through hole 12. This structural design allows the entire needle valve assembly to be connected and fixed to the spray gun body and trigger linkage through a simple insertion and removal action of the transverse pin 7. The entire assembly and disassembly process requires no tools and is extremely quick and convenient.

[0031] To further improve the long-term reliability and maintainability of the quick-release mechanism, this embodiment features a more detailed design of its internal structure. The locking assembly mounting hole 13 has an internal thread 14 at the end furthest from the seal 2 (i.e., towards the rear end of the connecting sleeve 1). The elastic locking assembly 6 includes a steel ball 61 and a pin-engaging spring 62. During assembly, the pin-engaging spring 62 and the steel ball 61 are first inserted sequentially from the open end of the mounting hole 13, and then screwed into the internal thread 14 using an adjusting screw 63. Firstly, it completely houses the small parts that are easily lost during disassembly and assembly—the steel ball 61 and the pin-engaging spring 62—and seals them with the adjusting screw 63, preventing component loss. Secondly, and most importantly, by adjusting the screw depth of the adjusting screw 63, the user can precisely and quantitatively adjust the compression of the pin-engaging spring 62, thereby freely changing the preload applied to the steel ball 61. When the product is new, a standard preload force with excellent feel and locking power can be set. When normal wear occurs on the pin 7 or the hole wall due to long-term use, creating gaps, the user does not need to replace any parts. Simply use a regular screwdriver to slightly tighten the adjusting screw 63 to increase the preload force, compensate for the wear gaps, and restore the original locking effect. This design extends the product's lifespan and improves maintainability.

[0032] To cooperate with the aforementioned elastic locking assembly 6, the transverse pin 7 has a positioning groove 71 in the middle of its rod portion for engaging with the steel ball 61 of the elastic locking assembly 6. When the transverse pin 7 is pushed into the transverse pin through hole 12 and reaches the correct working position, the steel ball 61, under the continuous push of the pin engaging spring 62, engages into the positioning groove 71 with a striking sound. This not only provides the operator with clear tactile and audible feedback, clearly indicating that the installation is in place, but more importantly, the cooperation between the steel ball and the groove forms a reliable positive locking structure that can effectively resist axial tension, preventing the pin 7 from accidentally slipping out during the violent vibration of the spray gun, ensuring absolute operational safety. When it needs to be pulled out, greater external force can be applied to remove it.

[0033] As a preferred geometric configuration, the positioning groove 71 has a V-shaped cross-section. The two inclined surfaces of the V-shaped groove can form a stable and reliable two-point contact with the spherical steel ball 61. Compared with U-shaped grooves or rectangular grooves, its positioning is more accurate. Moreover, during the insertion and removal process, the V-shaped inclined surfaces can play a guiding role, making the insertion and removal process smoother and providing a better operating feel.

[0034] For one embodiment, please refer to Figure 2This invention also provides a spray gun using the aforementioned needle valve assembly. The spray gun includes a gun body 8, on which a cavity 81 for housing the needle valve assembly and a user-operated handle 82 are provided. The handle 82 is rotatably connected to the cavity 81 (or the gun body 8). The outlet of the cavity 81 is provided with a detachable sealing cap 9, for example, connected by a thread. The sealing cap 9 has a through-hole 91, the inner end of which forms a valve seat. The needle valve assembly of this invention is completely housed within the cavity 81. A sealing spring 10 is also provided between the cavity 81 and the needle valve assembly. When the spray gun is stationary, the sealing spring 10 always applies a forward thrust to the needle valve assembly. This thrust causes the ball valve core 33 of the needle assembly 3 to tightly abut against the valve seat of the through-hole 91 of the sealing cap 9, thereby reliably sealing the cavity and preventing paint leakage. The movable handle 82 is connected to the connecting sleeve 1 of the needle valve assembly via the transverse pin 7. When the user pulls the movable handle 82, the handle 82 rotates around its fulcrum and, through the common connecting element of the transverse pin 7, pulls the entire needle valve assembly backward, causing it to move backward within the cavity 81. This movement compresses the sealing spring 10 and causes the ball valve core 33 to disengage from the valve seat of the discharge port 91, thereby opening the paint channel for spraying. When the user releases the movable handle 82, the elastic energy of the compressed sealing spring 10 is released, pushing the entire needle valve assembly to quickly return to its original position, causing the ball valve core 33 to tightly seal the discharge port 91 again, achieving a clean cut-off of material. Finally, it should be emphasized that the above-described embodiments are only used to illustrate the technical concept and preferred implementation of this utility model, and are not intended to exhaustively describe or limit the scope of protection of this utility model. Any person skilled in the art, after understanding the spirit and core technical solution of this utility model, may make various modifications, equivalent substitutions or improvements based on the content disclosed in this utility model without departing from the basic principles of this utility model. Such obvious modifications or substitutions should be considered as included within the protection scope claimed by this utility model.

Claims

1. A needle valve assembly, characterized in that, include: The seat (31) has a valve core mounting seat at its front end for mounting the ball valve core (33), and the opening diameter at the end of the valve core mounting seat is smaller than the diameter of the ball valve core (33). A gun needle rod (32) is inserted into the base (31), and a limit step (321) is provided at one end of the gun needle rod. The ball valve core (33); The needle rod (32), the seat (31), and the ball valve core (33) together constitute the needle assembly (3).

2. The needle valve assembly according to claim 1, characterized in that, The ball valve core (33) is connected to the valve core mounting seat by extrusion or riveting.

3. The needle valve assembly according to claim 1, characterized in that, Also includes: Connecting sleeve (1), the end of the gun needle assembly (3) is connected to the connecting sleeve (1); The sealing element (2) is passed through the gun needle rod and is disposed between the seat and the connecting sleeve (1); An internal preload spring (4) is provided between the seal (2) and the seat (31) to apply an axial preload force to the needle assembly (3) to eliminate the fit gap between the needle rod (32) and the seat (31).

4. The needle valve assembly according to claim 3, characterized in that, The sealing element (2) has an outer stepped surface (21), and the connecting sleeve (1) has an inner stepped surface (11) that abuts against the outer stepped surface (21). The outer stepped surface and the inner stepped surface cooperate to achieve axial positioning of the sealing element (2) within the connecting sleeve (1).

5. The needle valve assembly according to claim 3, characterized in that, The needle assembly (3) is fixed in the connecting sleeve (1) by at least two opposing set screws (5). The set screws are arranged radially along the connecting sleeve. The end of the needle rod is provided with a set groove (322), and the set screw can be locked in the set groove.

6. The needle valve assembly according to claim 3, characterized in that, The connecting sleeve (1) is provided with a transverse pin through hole (12) that extends radially through it; the connecting sleeve (1) is also provided with a locking component mounting hole (13) that opens axially along it, the side wall of the locking component mounting hole (13) is connected to the transverse pin through hole (12), and the locking component mounting hole (13) is provided with an elastic locking component (6) for elastically engaging with the transverse pin (7) inserted into the transverse pin through hole (12).

7. The needle valve assembly according to claim 6, characterized in that, The locking assembly mounting hole (13) is provided with an internal thread (14) at one end away from the seal (2); the elastic locking assembly (6) includes a steel ball (61) and a pin-locking spring (62), and the preload of the pin-locking spring (62) on the steel ball (61) can be adjusted by the depth of the adjusting screw (63) screwed into the internal thread (14).

8. The needle valve assembly according to claim 6, characterized in that, The transverse pin (7) has a positioning groove (71) in the middle of its rod for engaging with the steel ball (61) of the elastic locking assembly (6).

9. The needle valve assembly according to claim 8, characterized in that, The cross-section of the positioning groove (71) is V-shaped.

10. A spray gun, characterized in that, include: The spray gun body (8) is provided with a cavity (81) and a movable handle (82); the movable handle is rotatably connected to the cavity; the outlet of the cavity is provided with a threaded sealing cap (9), and the sealing cap is provided with a discharge hole (91). It also includes the needle valve assembly as described in any one of claims 6 to 9; The needle valve assembly is located inside the cavity (81). A sealing spring (10) is also provided between the cavity and the needle valve assembly. The sealing spring can press the ball valve core against the discharge hole to seal the cavity. The movable handle (82) is connected to the connecting sleeve (1) of the needle valve assembly through the transverse pin (7). When the movable handle (82) rotates, it can squeeze the sealing spring and drive the needle valve assembly to move inside the cavity (81) so that the ball valve core is separated from the discharge hole.

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