A three-screw auxiliary with good sealing and self-balancing

Abstract

The utility model belongs to three screw rod pump technical field, specifically discloses a three screw rod pair that good sealing and self -balancing, including driving screw rod and two driven screw rod, two driven screw rod symmetry sets up in the both sides of driving screw rod and is engaged with driving screw rod, driving screw rod includes the locating section A, spiral section A, first axle section, balance disc and second axle section that connect in proper order, driven screw rod includes the locating section B, spiral section B and connecting section that connect in proper order. The utility model provides a three screw rod pair that good sealing and self -balancing, conical section B and conical section A in actual operation process, increase the sealing surface at this place, and then enhance its sealing effect, and this increased sealing surface design not only effectively prevents fluid leakage, also significantly reduces the energy loss due to the sealing is not strict. Due to the improvement of sealing performance, the three screw rod pair can also keep stable running state under high pressure, high speed working environment, greatly prolongs the service life of equipment.

Description

Technical Field

[0001] This utility model relates to the field of three-screw pump technology, and in particular to a three-screw assembly with good sealing performance and self-balancing properties. Background Technology

[0002] A three-screw pump is a rotary positive displacement pump consisting of a driving screw (power screw), two driven screws (sealing screws), and a pump housing (pump body) containing them. It transports liquid by utilizing the uniform movement of the sealed chambers when the screws mesh. Specifically, the driving screw is located in the middle, and the two driven screws are symmetrically distributed on both sides. A series of continuous, sealed chambers, called "sealing chambers," are formed between the helical surfaces of the screws and between the screws and the inner wall of the pump housing. When the driving screw is driven to rotate by a motor, it drives the driven screws on both sides to rotate in the opposite direction. At the pump's suction end, the volume of these sealing chambers continuously increases, creating a vacuum, thereby drawing in liquid.

[0003] In conventional slotted three-screw pumps, such as Figure 1 As shown, the end of the main screw 200 is sequentially connected to shaft A 400, drive screw balance disk 300, and shaft B 700. Shaft A 400 has a flange 500 on its outside, forming a receiving cavity 600 between the flange 500 and the drive screw balance disk 300. The ends of the slave screws 100 on both sides of the main screw 200 are provided with mating bosses 800 that cooperate with the receiving cavity 600. The mating bosses 800 can be embedded in the receiving cavity 600. In this connection method, the cooperation between the mating bosses 800 and the receiving cavity 600 plays a positioning role for the main screw 200 and the slave screws 100. At the same time, the outer diameter of the drive screw balance disk 300 is the same as the outer diameter of the helical section of the main screw 200. This conventional slotted three-screw pump has a small sealing surface (i.e., the part that contacts the right side of the mating boss 800 and the left side of the drive screw balance disc 300). Therefore, when conveying low-viscosity media such as diesel, the sealing effect of this structure will decrease, resulting in some performance loss and reduced volumetric efficiency. This contradiction will be more obvious and prominent, especially under high-pressure and low-viscosity operating conditions.

[0004] In summary, the existing three-screw pumps suffer from reduced sealing performance due to their small sealing surface, which in turn leads to decreased performance and volumetric efficiency. Utility Model Content

[0005] This invention provides a three-screw assembly with good sealing performance and self-balancing, which can solve the problem in the prior art of three-screw pumps where the sealing effect is reduced due to the small sealing surface, which in turn leads to a decrease in performance and volumetric efficiency.

[0006] A self-balancing three-screw assembly with good sealing performance includes a driving screw and two driven screws. The two driven screws are symmetrically arranged on both sides of the driving screw and mesh with the driving screw. The driving screw includes a positioning section A, a helical section A, a first shaft section, a balance disc and a second shaft section connected in sequence. The driven screws include a positioning section B, a helical section B and a connecting section connected in sequence. The balance disc includes a conical section A and a cylindrical section A connected together, with one end of the cylindrical section A away from the conical section A connected to a second shaft section; The connecting section includes a conical section B and a cylindrical section B connected together, with one end of the cylindrical section B away from the conical section B connected to a helical section B; The conical segment B is paired with the conical segment A.

[0007] Furthermore, a positioning boss is provided at the end of the positioning segment A away from the spiral segment A, and a balance adjustment block is provided outside the positioning boss; The positioning segment B has a boss at one end away from the spiral segment B that cooperates with the balance adjustment block.

[0008] Furthermore, the balance adjustment block has a mounting hole that mates with the positioning boss, and the positioning boss is located in the mounting hole.

[0009] Furthermore, the positioning boss has a hollow cavity inside, and fasteners are installed inside the hollow cavity; The balance adjustment block is locked to the positioning boss by fasteners.

[0010] Furthermore, the inner surface of the hollow cavity is provided with a threaded portion, and the fastener engages with the threaded portion.

[0011] Furthermore, a shim is provided on the outside of the positioning boss, and the shim is located between the head of the fastener and the balance adjustment block.

[0012] Furthermore, a conical groove A is provided at the end of the balance adjustment block away from the spiral section A; A tapered groove B is provided at one end of the boss near the positioning section B, and the inner surface of the tapered groove B matches the inner surface of the tapered groove A.

[0013] Furthermore, the small end of the conical groove A and the small end of the conical segment A are both oriented towards the spiral segment A.

[0014] Furthermore, the large end of the conical groove B and the large end of the conical segment B are both oriented towards the spiral segment B.

[0015] Furthermore, the outer diameter of the spiral segment A is smaller than the outer diameter of the balance disc.

[0016] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model provides a three-screw assembly with good sealing performance and self-balancing, including a driving screw and two driven screws. The two driven screws are symmetrically arranged on both sides of the driving screw and mesh with it, enabling the driving screw to drive the two driven screws to rotate synchronously. The driving screw includes a positioning section A, a helical section A, a first shaft section, a balance disc, and a second shaft section connected sequentially from left to right. The driven screws include a positioning section B, a helical section B, and a connecting section connected sequentially from left to right. The helical section A on the driving screw meshes with the helical section B on the driven screws. The tight meshing of the helical section A and the helical section B on the driven screws achieves a high-efficiency transmission effect, enabling the two driven screws to rotate synchronously and stably following the driving screw. The first shaft section serves to connect and support the helical section A and the balance disc. The balance disc includes a conical section A and a cylindrical section A connected together. The end of the cylindrical section A furthest from the conical section A is connected to a second shaft section. Specifically, the conical section A is conical, with its larger end connected to the cylindrical section A and its smaller end connected to the first shaft section. Specifically, the larger end of the conical section A refers to the end with the larger diameter, which connects to the cylindrical section A. This structure allows the balance disc to better cooperate with surrounding components during rotation, achieving balance and stability. The smaller end of the conical section A, connected to the first shaft section, ensures that power can be smoothly transmitted from the first shaft section to the conical section A, thereby achieving stable operation of the entire screw assembly. The connecting section includes a conical section B and a cylindrical section B connected together. The end of the cylindrical section B furthest from the conical section B is connected to the helical section B. Specifically, the conical section B is tapered, and its larger end connects to the cylindrical section B. The larger end of the conical section B refers to the end with the larger diameter. The conical section B mates with the conical section A. This mating method allows for a tighter fit when they come into contact, effectively reducing gaps and enhancing sealing performance. Simultaneously, the taper design of the conical section B and the conical section A are matched, enabling them to support and balance each other during rotation, further improving the stability and operating efficiency of the entire three-screw assembly.

[0017] 2. In this invention, the conical section B and conical section A increase the sealing surface area during actual operation, thereby enhancing the sealing effect. In practical applications, this enlarged sealing surface design not only effectively prevents fluid leakage but also significantly reduces energy loss caused by poor sealing. Simultaneously, due to the improved sealing performance, the three-screw assembly can maintain stable operation even under high-pressure and high-speed working environments, greatly extending the service life of the equipment. Furthermore, the enlarged sealing surface also makes the three-screw assembly more adaptable and flexible in dealing with different media and operating conditions. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the slotted three-screw pump provided in the background art of this utility model; Figure 2 A schematic diagram of a three-screw assembly with good sealing performance and self-balancing provided by this utility model; Figure 3 A schematic diagram of the active screw of a three-screw assembly with good sealing performance and self-balancing, provided by this utility model; Figure 4 A schematic diagram of the structure of a balance adjustment block for a three-screw assembly with good sealing performance and self-balancing, provided by this utility model; Figure 5 Provided by this utility model Figure 2 Enlarged view of the structure at point A in the image; Figure 6 A schematic diagram of the driven screw of a three-screw assembly with good sealing performance and self-balancing, provided by this utility model; Figure 7 A schematic diagram of the connecting section of a three-screw assembly with good sealing performance and self-balancing, provided by this utility model; Figure 8 A partial structural diagram of the driven screw of a three-screw assembly with good sealing performance and self-balancing, provided for this utility model; Figure 9 A partial structural diagram of the driving screw of a three-screw assembly with good sealing performance and self-balancing, provided by this utility model.

[0019] Explanation of reference numerals in the attached figures: 100, Screw; 200, Main screw; 300, Driving screw balance disc; 400, Shaft A; 500, Flange; 600, Receiving cavity; 700, Shaft B; 800, Mating boss; 1. Drive screw; 11. Positioning section A; 111. Positioning boss; 112. Hollow cavity; 13. Gasket; 12. Helical section A; 13. First shaft section; 14. Balance disc 1; 141. Conical section A; 142. Cylindrical section A; 15. Second shaft section; 16. Fastener; 2. Driven screw; 21. Positioning section B; 22. Helical section B; 23. Connecting section; 231. Conical section B; 232. Cylindrical section B; 24. Boss; 25. Conical groove B; 3. Balance adjustment block; 31. Mounting hole; 32. Conical groove A. Detailed Implementation

[0020] The specific embodiments of this utility model are described in detail below, but it should be understood that the scope of protection of this utility model is not limited to the specific embodiments.

[0021] A three-screw pump is a rotary positive displacement pump consisting of a driving screw (power screw), two driven screws (sealing screws), and a pump housing (pump body) containing them. It transports liquid by utilizing the uniform movement of the sealed chambers when the screws mesh. Specifically, the driving screw is located in the middle, and the two driven screws are symmetrically distributed on both sides. A series of continuous, sealed chambers, called "sealing chambers," are formed between the helical surfaces of the screws and between the screws and the inner wall of the pump housing. When the driving screw is driven to rotate by a motor, it drives the driven screws on both sides to rotate in the opposite direction. At the pump's suction end, the volume of these sealing chambers continuously increases, creating a vacuum, thereby drawing in liquid.

[0022] In conventional slotted three-screw pumps, such as Figure 1 As shown, the end of the main screw 200 is sequentially connected to shaft A 400, drive screw balance disk 300, and shaft B 700. Shaft A 400 has a flange 500 on its outside, forming a receiving cavity 600 between the flange 500 and the drive screw balance disk 300. The ends of the slave screws 100 on both sides of the main screw 200 are provided with mating bosses 800 that cooperate with the receiving cavity 600. The mating bosses 800 can be embedded in the receiving cavity 600. In this connection method, the cooperation between the mating bosses 800 and the receiving cavity 600 plays a positioning role for the main screw 200 and the slave screws 100. At the same time, the outer diameter of the drive screw balance disk 300 is the same as the outer diameter of the helical section of the main screw 200. This conventional slotted three-screw pump has a small sealing surface (i.e., the part that contacts the right side of the mating boss 800 and the left side of the drive screw balance disc 300). Therefore, when conveying low-viscosity media such as diesel, the sealing effect of this structure will decrease, resulting in some performance loss and reduced volumetric efficiency. This contradiction will be more obvious and prominent, especially under high-pressure and low-viscosity operating conditions.

[0023] Furthermore, in actual operation, the driven screw 100 continuously bears the axial force toward the shaft of the main screw 200. This increases the friction between the sealing surfaces of the main screw 200 and the driven screw 100, which to some extent exacerbates the wear of the sealing surfaces. At the same time, since the force on the driven screw 100 is transmitted to the main screw 200, and the outer diameter of the driving screw balance disc 300 is the same as the outer diameter of the helical section of the main screw 200, the main screw 200 is subjected to an unbalanced force in the axial direction, which directly affects the stability of the product.

[0024] In summary, the existing three-screw pumps suffer from reduced sealing performance due to their small sealing surface, which in turn leads to decreased performance and volumetric efficiency.

[0025] Based on this, the present invention provides a three-screw pump screw pair that can both increase the sealing surface of the screw pair and enable the main and driven screws of the screw pair to achieve self-balancing.

[0026] like Figures 2 to 7 As shown, the present invention provides a three-screw assembly with good sealing performance and self-balancing, including a driving screw 1 and two driven screws 2. The two driven screws 2 are symmetrically arranged on both sides of the driving screw 1 and mesh with the driving screw 1. The driving screw 1 includes a positioning section A 11, a helical section A 12, a first shaft section 13, a balance disc 14, and a second shaft section 15 connected sequentially from left to right; the driven screw 2 includes a positioning section B 21, a helical section B 22, and a connecting section 23 connected sequentially from left to right; and the helical section A 12 on the driving screw 1 meshes with the helical section B 22 on the driven screw 2. The balance disc 14 includes a conical section A 141 and a cylindrical section A 142 connected together. The end of the cylindrical section A 142 away from the conical section A 141 is connected to the second shaft section 15. Specifically, the conical section A 141 is conical, and its large end is connected to the cylindrical section A 142, while its small end is connected to the first shaft section 13. Specifically, the large end of the conical section A 141 refers to the end with the larger diameter, which is connected to the cylindrical section A 142. This structure allows the balance disc 14 to better cooperate with surrounding components during rotation, achieving a balancing and stabilizing effect. The small end of the conical section A 141 is connected to the first shaft section 13, ensuring that power can be smoothly transmitted from the first shaft section 13 to the conical section A 141, thereby achieving stable operation of the entire screw assembly.

[0027] The connecting segment 23 includes a conical segment B 231 and a cylindrical segment B 232 connected together. The end of the cylindrical segment B 232 away from the conical segment B 231 is connected to the helical segment B 22. Specifically, the conical segment B 231 is conical, and the large end of the conical segment B 231 is connected to the cylindrical segment B 232. The large end of the conical segment B 231 refers to the end with the larger diameter in the conical segment B 231. The conical section B 231 and the conical section A 141 are fitted together; this fit allows for a tighter seal when they come into contact, effectively reducing gaps and enhancing sealing performance. Furthermore, the matching taper designs of the conical sections B 231 and A 141 ensure mutual support and balance during rotation, further improving the stability and operating efficiency of the entire three-screw assembly.

[0028] In actual operation, the increased sealing surface area of ​​conical sections B 231 and A 141 not only directly improves the contact range of the sealing surface but also further enhances its sealing effect. This increased sealing surface design is particularly important in practical applications. It effectively prevents fluid leakage, ensuring system safety and stability, and significantly reduces energy loss due to poor sealing, thereby improving overall operating efficiency. Furthermore, due to the significantly improved sealing performance, this three-screw assembly maintains stable and reliable operation even under extreme high-pressure and high-speed conditions. This not only reduces equipment failure rates but also greatly extends equipment lifespan and lowers maintenance costs.

[0029] Furthermore, the enlarged sealing surface brings another significant advantage: the three-screw assembly exhibits greater adaptability and flexibility when dealing with different media and complex operating conditions. Whether facing high-viscosity fluids or high-temperature, high-pressure environments, this design ensures that sealing performance remains unaffected, thereby guaranteeing the equipment's wide applicability and efficient operation. These multifaceted performance improvements give the three-screw assembly superior overall performance in practical applications.

[0030] Furthermore, both conical sections A 141 and B 231 are conical, and they fit together. Therefore, the force between the sealing surfaces on the driven screw 2 is reduced due to the taper of conical section B 231, which to some extent reduces wear on the sealing surfaces and extends their service life. Specifically, this conical structure design not only optimizes the force distribution on the sealing surfaces, making the pressure more evenly distributed and avoiding increased wear caused by local stress concentration, but also achieves effective control of friction between the sealing surfaces through fine-tuning of the taper. In actual operation, this design reduces the heat generated by friction, lowers the risk of decreased sealing performance due to thermal expansion of the sealing components, and thus ensures the stability and reliability of the three-screw pair during long-term operation. At the same time, the use of the conical structure also makes the fit between the driven screw and the driving screw more precise, improving the overall transmission efficiency.

[0031] like Figures 2 to 7 , Figure 9 As shown, in some embodiments of this utility model, the outer diameter of the helical segment A 12 is smaller than the outer diameter of the balance disc 14; it is used to balance the sum of the hydraulic force on the driving screw 1 and the force transmitted by the driven screw 2 during operation. Specifically, the inner side of the balance disk 14 on the active screw 1 is designed with a conical surface at an angle α. The angle α refers to the angle between the hypotenuse of the trapezoid and the lower base (i.e., the longer base) of the trapezoid, since the conical segment A 141 on the balance disk 14 is conical and its vertical cross section is trapezoidal. Simultaneously, the outer diameter of the balance disc 14 on the drive screw 1 is increased, and the dimension D of the balance disc 14 on the drive screw 1 is calculated using the following formula: ; Where, dj——the pitch circle diameter of the driving screw 1; D—Diameter of the balance disc 14 on the drive screw 1; p—Work pressure; F—The force transmitted from the driven screw to the driving screw through the conical surface; The size D of the balance disc 14 on the driving screw 1, calculated according to the above formula, can balance the sum of the hydraulic force on the driving screw 1 and the force transmitted by the driven screw 2 during operation. After calculation, the final size D > D1. Due to the increase in the size of the balance disc 14 on the driving screw 1, the sealing area formed by the inner side of the balance disc 14 on the driving screw 1 and the α-angle cone surface of the driven screw 2 near the outer side of the balance disc 14 on the driving screw 1 will increase, thereby improving the sealing performance and product performance.

[0032] like Figures 2 to 8 As shown, in some embodiments of this utility model, a positioning boss 111 is provided at one end of the positioning segment A11 away from the spiral segment A12, and a balance adjustment block 3 is provided outside the positioning boss 111; specifically, the balance adjustment block 3 has a mounting hole 31 that cooperates with the positioning boss 111, and the positioning boss 111 is located in the mounting hole 31, that is, the balance adjustment block 3 can be fitted and assembled with the positioning boss 111 through the mounting hole 31 on it; The end of the positioning section B 21 away from the spiral section B 22 is provided with a boss 24 that cooperates with the balance adjustment block 3; Specifically, a conical groove A32 is provided at the end of the balance adjustment block 3 away from the spiral section A12, and a conical groove B25 is provided at the end of the boss 24 near the positioning section B21. The inner surface of the conical groove B25 matches the inner surface of the conical groove A32. Furthermore, the small end of the conical groove A 32 and the small end of the conical segment A 141 are both oriented towards the spiral segment A 12, and the large end of the conical groove B 25 and the large end of the conical segment B 231 are both oriented towards the spiral segment B 22. In the above scheme, a boss 24 is provided on the positioning section B 21. The side of the boss 24 near the positioning section B 21 is designed to have a conical groove B 25. The conical surface of the conical groove B 25 is designed to be opposite to the conical surface of the conical section B 231 at the other end. That is, the larger end of the conical groove B 25 (i.e., the end with the longer diameter in the conical groove B 25) is close to the spiral section B 22, and the smaller end of the conical groove B 25 (i.e., the end with the shorter diameter in the conical groove B 25) is away from the spiral section B 22. On the other hand, the larger end of the conical section B 231 (i.e., the end with the longer diameter in the conical section B 231) is close to the spiral section B 22, and the smaller end of the conical section B 231 (i.e., the end with the shorter diameter in the conical section B 231) is away from the spiral section B 22. This achieves the purpose of the conical surface of the conical groove B 25 being opposite to the conical surface of the conical section B 231. In addition, such as Figure 4 As shown, the conical groove A 32 also features a conical surface design with an α angle. This α angle refers to the angle between the hypotenuse of the trapezoid and the lower base (the longer side of the base) of the trapezoid, given that the conical groove A 32 is conical and its vertical cross-section is trapezoidal. Figure 4 In this context, angle α is a corresponding angle, meaning the angles are the same. Similarly, as Figure 8 As shown, the inner surface of the conical groove B 25 mates with the inner surface of the conical groove A 32. Therefore, the conical groove B 25 also features a conical surface design with an α angle. This α angle refers to the angle between the hypotenuse of the trapezoid and the lower base (the longer side of the base) of the trapezoid, since the conical groove B 25 is conical, its vertical cross-section is trapezoidal. Figure 8 In this context, angle α is a corresponding angle, meaning the angles are the same. In the specific analysis process, such as Figure 8 As shown, the driven screw 2 is always subjected to axial force toward the shaft head (i.e., the first shaft section 13, the balance disc 14, and the second shaft section 15) of the driving screw 1 in actual working state. As for the α-angle conical surfaces (i.e., the conical surface of the conical section B 231 and the conical surface of the conical groove B 25) at both ends of the driven screw 2, the forces F1 and F2 acting on the conical surfaces of the conical section B 231 and the conical surface of the conical groove B 25 can be decomposed into two components perpendicular to the conical surface and parallel to the conical surface, namely F11, F12 and F21, F22, respectively. Since F1=F2 and the cone angle α is also equal, F11=F21 and F12=F22. Because the directions of the equal component forces tend to be opposite, after the component forces are further decomposed, they will form equal and opposite component forces in the radial direction (perpendicular to the screw axis). This allows the driven screw 2 to achieve radial force balance. At the same time, the component force perpendicular to the cone surface at angle α will be reduced compared to the original force. As a result, the sealing surface formed by the cone surface at angle α on the inner side of the balance disc 14 on the driving screw 1 and the outer side of the cone surface at angle α near the end of the balance disc 14 on the driven screw 2 (i.e., the side where the cone section A 141 and the cone section B 231 contact) will also be reduced, wear will be reduced, and service life will be extended.

[0033] Furthermore, a conical groove A32 is provided at the end of the balance adjustment block 3 away from the spiral segment A12. The conical surface of the conical groove A32 is designed to be opposite to the conical surface of the conical segment A141 at the other end. That is, the small end of the conical groove A32 (i.e., the end with the shorter diameter in the conical groove A32) is set close to the spiral segment A12, and the large end of the conical groove A32 (i.e., the end with the longer diameter in the conical groove A32) is set away from the spiral segment A12; while the small end of the conical segment A141 (i.e., the end with the shorter diameter in the conical segment A141) is set close to the spiral segment A12, and the large end of the conical segment A141 (i.e., the end with the longer diameter in the conical segment A141) is set away from the spiral segment A12; thus achieving the purpose of the conical surface of the conical groove A32 being opposite to the conical surface of the conical segment A141 at the other end.

[0034] like Figures 2 to 9 As shown, in some embodiments of this utility model, a hollow cavity 112 is provided inside the positioning boss 111, and a fastener 16 is provided inside the hollow cavity 112. The balance adjustment block 3 is locked to the positioning boss 111 by the fastener 16; the inner surface of the hollow cavity 112 is provided with a threaded part, and the fastener 16 is engaged with the threaded part. In this invention, a positioning section (i.e., positioning section A 11) is designed at the tail end of the active screw 1. The positioning section A 11 is provided with a fastening thread (i.e., the threaded part inside the hollow cavity 112) and a positioning boss 111. At the same time, a balance adjustment block 3 is designed. The balance adjustment block 3 has a positioning hole (i.e., mounting hole 31) that can be fitted with the active screw 1. At the same time, the balance adjustment block 3 is provided with a conical surface (i.e., conical groove A 32) opposite to the balance disc 14 of the active screw, which can be fitted with the conical groove B 25 on the driven screw 2. In this way, the force on the driven screw 2 on the two opposite conical surfaces can be decomposed into equal and opposite components in the radial direction, and the driven screw 2 is balanced in the radial direction.

[0035] like Figures 2 to 9As shown, in some embodiments of this utility model, a shim 113 is also provided on the outside of the positioning boss 111, and the shim 113 is provided between the head of the fastener 16 and the balance adjustment block 3. The outer diameter of the gasket 113 is larger than the inner diameter of the hollow cavity 112, and the outer diameter of the gasket 113 is larger than the inner diameter of the mounting hole 31. By screwing the fastener 16 into the hollow cavity 112 and engaging with the threaded portion inside the hollow cavity 112, the gasket 113 is pressed against the balance adjustment block 3 by tightening the fastener 16, thereby fixing the balance adjustment block 3 to the tail end of the drive screw 1.

[0036] like Figure 3 and Figure 4 As shown, in some embodiments of this utility model, the inner diameter of the mounting hole 31 is marked as d2, and the outer diameter of the positioning boss 111 is marked as D2, d2=D2, so that the balance adjustment block 3 can be installed on the positioning boss 111 through the mounting hole 31, and then fixed on the positioning boss 111 by the fastener 16, so as to achieve the purpose of assembling the balance adjustment block 3 with the active screw 1.

[0037] The above-disclosed embodiments are only a few specific examples of the present utility model. However, the embodiments of the present utility model are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the protection scope of the present utility model.

[0038] In the description of this utility model, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0039] In the description of this utility model, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

Claims

1. A self-balancing three-screw assembly with good sealing performance, comprising a driving screw (1) and two driven screws (2), wherein the two driven screws (2) are symmetrically arranged on both sides of the driving screw (1) and mesh with the driving screw (1), characterized in that, The driving screw (1) includes a positioning section A (11), a helical section A (12), a first shaft section (13), a balance disc (14), and a second shaft section (15) connected in sequence. The driven screw (2) includes a positioning section B (21), a helical section B (22), and a connecting section (23) connected in sequence. The balance disc (14) includes a conical section A (141) and a cylindrical section A (142) connected to each other, and one end of the cylindrical section A (142) away from the conical section A (141) is connected to a second shaft section (15). The connecting segment (23) includes a conical segment B (231) and a cylindrical segment B (232) connected to each other, and one end of the cylindrical segment B (232) away from the conical segment B (231) is connected to the helical segment B (22). The conical segment B (231) is paired with the conical segment A (141).

2. The three-screw assembly with good sealing performance and self-balancing according to claim 1, characterized in that, The positioning section A (11) is provided with a positioning boss (111) at one end away from the spiral section A (12), and a balance adjustment block (3) is provided outside the positioning boss (111). The positioning segment B (21) is provided with a boss (24) at one end away from the spiral segment B (22) that cooperates with the balance adjustment block (3).

3. The three-screw assembly with good sealing performance and self-balancing according to claim 2, characterized in that, The balance adjustment block (3) has a mounting hole (31) that cooperates with the positioning boss (111), and the positioning boss (111) is located in the mounting hole (31).

4. A three-screw assembly with good sealing performance and self-balancing according to claim 3, characterized in that, The positioning boss (111) has a hollow cavity (112) inside, and a fastener (16) is provided inside the hollow cavity (112). The balance adjustment block (3) is locked onto the positioning boss (111) by fasteners (16).

5. A three-screw assembly with good sealing performance and self-balancing according to claim 4, characterized in that, The hollow cavity (112) has a threaded part on its inner surface, and the fastener (16) is engaged with the threaded part.

6. A three-screw assembly with good sealing performance and self-balancing according to claim 4, characterized in that, The positioning boss (111) is also provided with a gasket (113) on the outside, and the gasket (113) is located between the head of the fastener (16) and the balance adjustment block (3).

7. A three-screw assembly with good sealing performance and self-balancing according to claim 2, characterized in that, A conical groove A (32) is provided at one end of the balance adjustment block (3) away from the spiral section A (12); A tapered groove B (25) is provided on one end of the boss (24) near the positioning section B (21), and the inner surface of the tapered groove B (25) matches the inner surface of the tapered groove A (32).

8. A three-screw assembly with good sealing performance and self-balancing according to claim 7, characterized in that, The small end of the conical groove A (32) and the small end of the conical segment A (141) are both oriented toward the spiral segment A (12).

9. A three-screw assembly with good sealing performance and self-balancing according to claim 7, characterized in that, The large end of the conical groove B (25) and the large end of the conical segment B (231) are both oriented toward the spiral segment B (22).

10. A three-screw assembly with good sealing performance and self-balancing according to claim 1, characterized in that, The outer diameter of the spiral segment A (12) is smaller than the outer diameter of the balance disc (14).

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