Low-noise three-screw pump and ship hydraulic system

Abstract

The present application relates to the technical field of positive displacement fluid machinery, and particularly relates to a low-noise three-screw rod pump and a ship hydraulic system. The low-noise three-screw rod pump comprises a new active screw rod, a positioning sleeve, two new driven screw rods, and a smooth section. The positioning sleeve is provided on the smooth section of the new active screw rod in an interference fit. The positioning sleeve is provided with an annular limiting groove. The two new driven screw rods are symmetrically matched with the new active screw rod. The front end of the new driven screw rod is provided with a cylindrical guide section. The cylindrical guide section is rotatably embedded in the annular limiting groove. The circumferential surface of the cylindrical guide section is provided with a tapered oil guide surface. The tapered oil guide surface is clamped between the inner wall of the bushing and the annular limiting groove with a set radial gap. The low-noise three-screw rod pump and the ship hydraulic system solve the technical problems of vibration noise increase caused by the large axial installation gap and the radial thermal expansion and jamming.

Description

Technical Field

[0001] This invention relates to the field of positive displacement fluid machinery technology, specifically to a low-noise three-screw pump and a marine hydraulic system. Background Technology

[0002] Currently, the three-screw pump, as an important rotary positive displacement pump, is widely used in oil transportation, chemical processes, marine hydraulic systems, and lubrication engineering due to its advantages such as stable flow, low pressure pulsation, and strong self-priming capability. With the development of high-end equipment manufacturing and increasingly stringent environmental standards, application scenarios are placing more stringent requirements on the low-noise operation of three-screw pumps.

[0003] In related technologies, such as Figure 1 , Figure 2 and Figure 3 As shown, existing three-screw pumps typically include components such as a pump body 1, a front cover 2, a sealing gland 3, a bushing 4, a driving screw 5, two driven screws 6, a bearing 7, a balance sleeve 8, a mechanical seal 9, a retaining ring 10, and a rear cover 12. Specifically, the bushing 4 is coaxially mounted inside the pump body 1. The driving screw 5 and two driven screws 6 are all mounted inside the bushing 4, with the outward-extending portion of the driving screw 5 passing through the sealing gland 3 and the mechanical seal 9. The front cover 2 is fixed to the front side of the bushing 4 and the pump body 1, and the rear cover 12 is fixed to the rear side of the bushing 4 and the pump body 1. The sealing gland 3 and the mechanical seal 9 are located outside the front cover 2. The driving screw 5 consists of a threaded section and a smooth section. The threaded section matches the driven screws 6, while the smooth section has a stepped shaft section with a larger diameter. The balance sleeve 8 is fitted onto the smooth section and is tightly attached to the stepped shaft section. The balance sleeve 8 is provided with two inward-facing and strictly symmetrical cylindrical grooves 14. The two cylindrical grooves 14 are used to accommodate the front ends of the two driven screws 6. The front ends of the driven screws 6 rotate in the cylindrical grooves 14, and the rear ends of the two driven screws 6 are held by the retaining rings 10.

[0004] However, existing three-screw pumps generally have the following defects during operation: 1) Traditional three-screw pumps use a retaining ring 10 and a balance sleeve 8 for single-point positioning (i.e., the front ends of the two driven screws 6 are fitted into the cylindrical groove 14 of the balance sleeve 8 and rotate within the cylindrical groove 14). To facilitate assembly, a certain axial installation gap 13 is reserved at both ends of the driven screws 6 during the design. However, after actual processing and assembly, this axial installation gap 13 is usually greatly affected by the closed dimension chain composed of the screw length, the thickness of the retaining ring, the depth of the cylindrical groove 14 of the balance sleeve, and the depth of the pump body cavity 1. It is easy for the axial installation gap 13 to be too large in the actual processing and assembly. This will cause the two driven screws 6 to be affected by hydraulic pressure, friction and meshing force, which will easily cause axial movement, resulting in increased vibration and noise. 2) The balance sleeve 8 is single-point positioned. The front end of the driven screw 6 is matched with the cylindrical groove 14 of the balance sleeve 8. The radial clearance is not adjustable. The assembly is heavily dependent on the machining accuracy of the parts. When running at high temperature, the screw has no compensation space for thermal expansion, which can easily cause jamming and increase vibration and noise. Summary of the Invention

[0005] This application provides a low-noise three-screw pump and a marine hydraulic system, which solves the technical problems of increased vibration and noise caused by excessive axial installation clearance leading to axial movement and radial thermal expansion and jamming.

[0006] In a first aspect, embodiments of this application provide a low-noise three-screw pump, comprising: New active screw; A positioning sleeve, which is interference-fitted onto the smooth section of the new drive screw, has an annular limiting groove. Two new driven screws are symmetrically matched with the new driving screw. The front end of the new driven screw is provided with a cylindrical guide section, which can be rotatably embedded in the annular limiting groove. The cylindrical guide section is provided with a conical oil guiding surface in the circumference, and the conical oil guiding surface is clamped between the inner wall of the bushing and the annular limiting groove according to a set radial clearance range.

[0007] In conjunction with the first aspect, in one embodiment, the positioning sleeve is provided with a first small stepped cylinder and a second large stepped cylinder, the diameters of which are both larger than the main body diameter of the positioning sleeve; the first small stepped cylinder and the second large stepped cylinder clamp together to form the annular limiting groove.

[0008] In conjunction with the first aspect, in one embodiment, the front end of the new driven screw is further provided with a cylindrical stepped section, the diameter of which is equal to the diameter of the cylindrical guide section; the cylindrical stepped section and the cylindrical guide section are sandwiched to form an annular groove, and the first small stepped cylinder can be rotatably embedded in the annular groove.

[0009] In conjunction with the first aspect, in one embodiment, the low-noise three-screw pump further includes a locating pin that radially penetrates the locating sleeve and is fixed to the new drive screw.

[0010] In conjunction with the first aspect, in one embodiment, the low-noise three-screw pump further includes a bearing and a new front cover, wherein the inner ring of the bearing is fitted onto the main body diameter portion on the front side of the second large stepped cylinder of the positioning sleeve; and the outer ring of the bearing is circumferentially clamped by the new front cover.

[0011] In conjunction with the first aspect, in one embodiment, the new front cover is alternately connected to the pump body side and the bushing side by screws and / or bolts.

[0012] In conjunction with the first aspect, in one embodiment, the taper of the tapered oil guide surface is 1:20. In conjunction with the first aspect, in one embodiment, the low-noise three-screw pump further includes a new sealing gland, which is mechanically fitted onto the smooth section of the new drive screw located above the positioning sleeve; the new sealing gland is provided with a rearward-facing abutting ring, which abuts against the front end face of the outer ring of the bearing; the rear end of the mechanical seal moving ring abuts against the front end face of the positioning sleeve.

[0013] In conjunction with the first aspect, in one embodiment, an O-ring seal is provided at the clearance mating surface between the pump body and the bushing for sealing.

[0014] Secondly, embodiments of this application provide a marine hydraulic system in which the aforementioned low-noise three-screw pump is installed.

[0015] The beneficial effects of the technical solutions provided in this application include: 1. Compared to traditional three-screw pumps that use retaining rings and balance sleeves for axial positioning at both ends, the complex closed dimensional chain can easily lead to excessive axial installation clearance at both ends of the driven screw. During operation, the driven screw is affected by hydraulic pressure, friction, and meshing forces, which can easily cause axial movement, resulting in screw meshing misalignment, increased friction and impact, and directly causing high vibration and high noise. The low-noise three-screw pump of this application has a cylindrical guide section at the front end of the new driven screw. The cylindrical guide section can be rotatably embedded in the annular limiting groove to form a precise axial positioning structure. Because it mainly relies on the cylindrical guide section and the annular limiting groove, the axial dimensional chain is simple, avoiding the machining deviation caused by the complex dimensional chain, achieving precise axial positioning, significantly reducing driven screw runout, improving meshing accuracy, and significantly reducing noise and vibration. Furthermore, compared to the traditional three-screw pump where the front ends of the two driven screws are tightly fitted at a single point within the cylindrical groove of the balance sleeve and rotate within the groove, the front end of the driven screw is circumferentially fitted within the cylindrical groove. Assembly is strictly dependent on the precision of the parts' machining, making machining difficult. If the clearance is too small, the screw's thermal expansion during high-temperature operation has no compensation space, easily leading to jamming and increased vibration and noise. If the clearance is too large, radial wear will occur, also resulting in increased vibration and noise. The low-noise three-screw pump of this application features a conical oil guide surface on the cylindrical guide section of the new driven screw. This conical oil guide surface facilitates oil guidance. More importantly, the conical oil guide surface is not fully fitted but only partially within the bushing. The circumferential inner wall of the bushing and the annular limiting groove restricts the radial dimension accuracy to a certain extent, reducing the machining difficulty. Furthermore, the radial dimension chain of the conical oil guide surface is simple, ensuring that the conical oil guide surface is clamped between the bushing inner wall and the annular limiting groove according to the set radial clearance range. Under the premise of ensuring precise centering, the conical oil guide surface has a certain thermal expansion compensation space, which solves the problem that the radial clearance is too large or too small in traditional three-screw pumps with strict radial accuracy. It eliminates or reduces the jamming of thermal expansion, avoids radial movement wear, and reduces vibration and noise. Overall, it provides a low-noise three-screw pump with good practicality and high application value.

[0016] Meanwhile, the new driven screw has no constraint at the lower end, which provides a rearward thermal expansion margin for high-temperature operating conditions, avoids jamming and wear, ensures stable and controllable internal leakage, and maintains stable volumetric efficiency over a long period of time.

[0017] 2. Compared to the traditional three-screw pump where the bearing periphery consists of a stepped cylinder, front cover, sealing gland, and mechanical seal related to the drive screw, the bearing periphery of the low-noise three-screw pump of this application only consists of a positioning sleeve, a new sealing gland, and a positioning pin. The bearing and positioning sleeve can be assembled first and then installed as a whole, reducing installation difficulty, simplifying the bearing periphery positioning structure, streamlining the complex connection structure at the front end of the traditional three-screw pump, and making the assembly path clearer.

[0018] 3. Compared to traditional three-screw pumps where the outer side of the bushing is in direct contact with the pump body, the pump body and bushing use a clearance fit. During operation, the rotation of the screw causes the bushing and pump body to collide, resulting in increased vibration and noise in the three-screw pump. The low-noise three-screw pump of this application has a rubber O-ring installed between the pump body and the bushing. When the three-screw pump is running, the pump body and bushing do not directly contact each other, reducing vibration and noise. In addition, the O-ring can reduce internal leakage of the three-screw pump and improve volumetric efficiency. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a three-screw pump in the prior art; Figure 2 This is a schematic diagram of the driven screw positioning structure of a three-screw pump in the prior art; Figure 3 This is a schematic diagram of the installation of the pump body and bushing of a conventional three-screw pump. Figure 4 This is a schematic diagram of the structure of a three-screw pump provided in an embodiment of this application; Figure 5 A schematic diagram of the driven screw positioning structure of a three-screw pump provided in an embodiment of this application; Figure 6 This is a schematic diagram of the installation of the driven screw pump body and bushing in this application; In the diagram: 1. Pump body; 2. Front cover; 3. Sealing gland; 4. Bushing; 5. Driving screw; 6. Driven screw; 7. Bearing; 8. Balance sleeve; 9. Mechanical seal; 10. Retaining ring; 12. Rear cover; 13. Axial installation clearance; 14. Cylindrical groove; 15. Clearance fit surface; 101. New front cover; 102. New sealing gland; 103. New drive screw; 104. New driven screw; 105. Positioning sleeve; 106. O-ring seal; 107. Positioning pin; 1051. Annular limiting groove; 1052. First small stepped cylinder; 1053. Second large stepped cylinder; 1041. Cylindrical guide section; 10411. Conical oil guide surface; 1042. Cylindrical stepped section; 1043. Annular groove. Detailed Implementation

[0021] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0022] This application provides a low-noise three-screw pump and a marine hydraulic system, which solves the technical problems of increased vibration and noise caused by excessive axial installation clearance leading to axial movement and radial thermal expansion and jamming.

[0023] like Figures 4 to 6 As shown, this application discloses an embodiment of a low-noise three-screw pump, which includes a new driving screw 103, a positioning sleeve 105, and two new driven screws 104.

[0024] Among them, the new active screw 103 eliminates the stepped cylinder at the original smooth section compared to the traditional active screw 5.

[0025] The positioning sleeve 105 is interference-fitted onto the smooth section of the new drive screw 103, and the positioning sleeve 105 has an annular limiting groove 1051. Specifically, the positioning sleeve 105 is fitted onto the smooth section of the new drive screw 103 near the front end of the threaded section.

[0026] Two new driven screws 104 are symmetrically matched with the new driving screw 103. Each new driven screw 104 has a cylindrical guide section 1041 at its front end, which can be rotatably embedded in an annular limiting groove 1051. A tapered oil guide surface 10411 is provided circumferentially on the cylindrical guide section 1041, and the tapered oil guide surface 10411 is clamped between the inner wall of the bushing 4 and the annular limiting groove 1051 according to a set radial clearance range. Specifically, the set radial clearance range is a radial clearance size range with a very small variation margin.

[0027] Specifically, the cylindrical guide section 1041 on the new driven screw 104 also serves to balance the axial force of the new driven screw, thus eliminating the need for the balance sleeve 8. Specifically, the positioning mating surface is a tapered oil guide surface 10411, which is connected to the fluid channel inside the pump body 1 to form a self-lubricating and forced cooling circuit.

[0028] Specifically, the new active screw 103 is installed inside the bushing 4 and mates with the central hole of the bushing 4. Two new driven screws 104 are symmetrically installed inside the bushing 4 and mate with the holes on both sides of the bushing 4. The bushing 4 is installed inside the pump body 1.

[0029] Compared to traditional three-screw pumps that use retaining rings 10 and balance sleeves 8 for axial positioning at both ends, the complex closed dimensional chain can easily lead to an excessively large axial installation clearance 13 at both ends of the driven screw 6. During operation, the driven screw 6 is affected by hydraulic pressure, friction, and meshing force, which can easily cause axial movement, resulting in screw meshing misalignment, increased friction and impact, and directly causing high vibration and high noise. The low-noise three-screw pump of this application has a cylindrical guide section 1041 at the front end of the new driven screw 104. The cylindrical guide section 1041 can be rotatably embedded in the annular limiting groove 1051 to form a precise axial positioning structure. Because it mainly relies on the cylindrical guide section 1041 and the annular limiting groove 1051, the axial dimensional chain is simple, avoiding the machining deviation caused by the complex dimensional chain, achieving precise axial positioning, significantly reducing the runout of the driven screw 6, improving meshing accuracy, and significantly reducing noise and vibration.

[0030] Furthermore, compared to the traditional three-screw pump where the front ends of the two driven screws 6 are tightly fitted at a single point in the cylindrical groove 14 of the balance sleeve 8 and rotate within the cylindrical groove 14, the front ends of the driven screws 6 are circumferentially fitted within the cylindrical groove 14. Assembly is strictly dependent on the precision of parts machining, making machining difficult. If the clearance is too small, there is no compensation space for the thermal expansion of the screws during high-temperature operation, which can easily lead to jamming and increased vibration and noise. If the clearance is too large, radial axial wear will occur, which will also lead to increased vibration and noise. In the low-noise three-screw pump of this application, the cylindrical guide section 1041 of the new driven screw 104 is provided with a conical oil guide surface 10411. The conical oil guide surface 10411 facilitates oil guidance. More importantly, firstly, the conical oil guide surface 10411 is not fully fitted but only partially covered by the bushing 4. The circumferential inner wall and the annular limiting groove 1051 restrict the radial dimension to a certain extent, reducing the strict accuracy requirements and machining difficulty. Furthermore, the radial dimension chain of the conical oil guide surface 10411 is simple, ensuring that it fits and is clamped between the inner wall of the bushing 4 and the annular limiting groove 1051 within the set radial clearance range. While ensuring precise centering, the conical oil guide surface 10411 has a certain thermal expansion compensation space, solving the problem of excessively large or small radial clearances in traditional three-screw pumps with strict radial accuracy. This eliminates or reduces thermal expansion jamming, avoids radial runout wear, and reduces vibration and noise, thus providing a low-noise three-screw pump with good practicality and high application value. Simultaneously, the new driven screw 104 has no constraint at its lower end, reserving backward thermal expansion margin for high-temperature conditions, avoiding wear caused by jamming, ensuring stable and controllable internal leakage, and maintaining long-term stable volumetric efficiency.

[0031] Furthermore, in one embodiment, the positioning sleeve 105 is provided with a first small stepped cylinder 1052 and a second large stepped cylinder 1053, the diameters of which are both larger than the main body diameter of the positioning sleeve 105. The first small stepped cylinder 1052 and the second large stepped cylinder 1053 clamp together to form an annular limiting groove 1051.

[0032] The three-screw pump of this application mainly relies on the first small stepped cylinder 1052 and the second large stepped cylinder 1053 to perform axial bidirectional positioning of the cylindrical guide section 1041.

[0033] Furthermore, the front end of the new driven screw 104 is provided with a cylindrical stepped section 1042, the diameter of which is the same as the diameter of the cylindrical guide section 1041.

[0034] The cylindrical stepped section 1042 and the cylindrical guide section 1041 are sandwiched to form an annular groove 1043, and the first small stepped cylinder 1052 is embedded in the annular groove 1043.

[0035] Specifically, from front to back, the structure consists of the second large stepped cylinder 1053, the cylindrical guide section 1041 which can be rotatably embedded in the annular limiting groove 1051, the first small stepped cylinder 1052 which can be rotatably embedded in the annular groove 1043, and the cylindrical stepped section 1042.

[0036] Specifically, the cylindrical guide section 1041 is embedded in the annular limiting groove 1051 according to the set axial clearance range, which is simple in terms of dimensions and easy to ensure machining accuracy.

[0037] Specifically, the first small stepped cylinder 1052 is embedded in the annular groove 1043 according to the set axial clearance range. The dimensional chain is simple and the machining accuracy is easy to guarantee.

[0038] The three-screw pump of this application has a composite embedded structure formed by the new driven screw 104 and the positioning sleeve 105, which improves the axial limiting capability and ensures stable axial limiting.

[0039] Furthermore, in one embodiment, the low-noise three-screw pump also includes a locating pin 107, which radially penetrates the locating sleeve 105 and is fixed to the new drive screw 103. The locating pin 107 further enhances the connection stability based on the interference fit between the locating sleeve 105 and the new drive screw 103.

[0040] Furthermore, in one embodiment, the low-noise three-screw pump also includes a bearing 7 and a new front cover 101, wherein the inner ring of the bearing 7 is fitted onto the main body diameter portion in front of the second large stepped cylinder 1053 of the positioning sleeve 105; the outer ring of the bearing 7 is circumferentially clamped by the new front cover 101.

[0041] Furthermore, in one embodiment, the new front cover 101 is connected to the side end of the pump body 1 and the side end of the bushing 4 by screws and / or bolts at equal angular intervals.

[0042] Specifically, for example, along the circumferential direction, the following sequence is followed: new front cover 101 screws are installed on bushing 4, new front cover 101 bolts are installed on pump body 1, new front cover 101 screws are installed on bushing 4, new front cover 101 bolts are installed on pump body 1, new front cover 101 screws are installed on bushing 4, and new front cover 101 bolts are installed on pump body 1.

[0043] Furthermore, in one embodiment, the tapered oil guide surface 10411 has a taper of 1:20 to achieve self-lubrication.

[0044] Furthermore, in one embodiment, the low-noise three-screw pump further includes a new sealing gland 102, which is fitted onto the smooth section of the new drive screw 103 above the positioning sleeve 105 via a mechanical seal 9; the new sealing gland 102 is provided with a rearward-facing abutting ring, which abuts against the front end face of the outer ring of the bearing 7. The rear end of the moving ring of the mechanical seal 9 abuts against the front end face of the positioning sleeve 105.

[0045] Specifically, the new front cover 101 is also connected to the new sealing cover 102 by bolts at the other end. The mechanical seal 9 is set inside the new sealing cover 102 and is fitted on the smooth section of the new active screw 103. The lower end of the moving ring of the mechanical seal 9 is positioned by the positioning sleeve 105.

[0046] The stationary ring of the mechanical seal 9 is installed on the new sealing gland 102. The mechanical seal 9 is cooled by the oil flowing in the pump's internal circuit. The bearing 7 is installed on the positioning sleeve 105 by interference fit at the connection between the bushing 4 and the new front cover 101.

[0047] Compared to the traditional three-screw pump where the bearing 7 is surrounded by a stepped cylinder, front cover 2, sealing gland 3, and mechanical seal 9, the bearing 7 of the low-noise three-screw pump of this application is only surrounded by a positioning sleeve 105, a new sealing gland 102, and a positioning pin 107. The bearing 7 and positioning sleeve 105 can be installed first and then the whole pump can be installed, which reduces the installation difficulty, simplifies the positioning structure around the bearing 7, and simplifies the complex connection structure at the front end of the traditional three-screw pump, making the assembly path clearer.

[0048] Compared to traditional three-screw pumps, which are assembled from scattered components such as retaining ring 10, balance sleeve 8, and multiple fasteners at the front end, resulting in complex structures, cumbersome disassembly and assembly steps, numerous parts leading to multiple failure points, difficult maintenance, and short service life, the low-noise three-screw pump of this application eliminates the balance sleeve 8 and retaining ring 10. It uses positioning sleeve 105 to integrate axial positioning and radial guidance, lubrication and cooling, and bearing installation functions. The bushing 4, pump body 1, and new front cover 101 are bolted together. With fewer parts, a clear assembly path, and a compact and simplified structure, the assembly and maintenance efficiency is improved. The low-friction mating pair and reliable cooling and lubrication result in less wear, longer service life, and suitability for medium and low pressure, long-life operation requirements.

[0049] like Figure 6 As shown, an O-ring 106 is further provided at the clearance mating surface 15 between the pump body 1 and the bushing 4 for sealing. The O-ring 106 between the bushing 4 and the pump body 1 is used to seal the medium and isolate the high and low pressure chambers.

[0050] Compared to Figure 3 In the conventional three-screw pump, the outer side of the bushing 4 is in direct contact with the pump body 1. Since the pump body 1 and the bushing 4 are fitted with a clearance, the rotation of the screw during operation will cause the bushing 4 and the pump body 1 to collide, resulting in increased vibration and noise of the three-screw pump. The low-noise three-screw pump of this application has a rubber O-ring installed between the pump body 1 and the bushing 4. When the three-screw pump is running, the pump body 1 and the bushing 4 do not directly contact each other, reducing vibration and noise. In addition, the O-ring can reduce internal leakage of the three-screw pump and improve volumetric efficiency.

[0051] Furthermore, in traditional three-screw pumps, the driving and driven screws are machined using profile milling, resulting in poor thread roughness. During high-speed operation, sharp points on the screw meshing surface lead to high-intensity meshing excitation, further increasing vibration and noise in the three-screw pump. The new driving screw 103 and new driven screw 104 of the low-noise three-screw pump in this application utilize high-precision screw profile machining equipment to improve the machining accuracy of the screw surface, ensuring the precision of screw meshing. An additional grinding process is added to further eliminate residual sharp points from screw machining, reducing noise and vibration in the three-screw pump.

[0052] Preferably, the positioning sleeve 105 adopts a wear-resistant alloy inlay structure, forming a low-friction, high-wear-resistant mating pair with the new driven screw 104.

[0053] Secondly, this application discloses an embodiment of a marine hydraulic system in which the aforementioned low-noise three-screw pump is installed.

[0054] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and 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, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" 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; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0055] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0056] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A low-noise three-screw pump, characterized in that, Include: New active screw (103); A positioning sleeve (105) is interference-fitted onto the smooth section of the new active screw (103), and the positioning sleeve (105) has an annular limiting groove (1051). Two new driven screws (104) are symmetrically matched with the new driving screw (103). The front end of the new driven screw (104) is provided with a cylindrical guide section (1041). The cylindrical guide section (1041) can be rotatably embedded in the annular limiting groove (1051). The cylindrical guide section (1041) is provided with a conical oil guide surface (10411) in the circumference. The conical oil guide surface (10411) is clamped between the inner wall of the bushing (4) and the annular limiting groove (1051) according to a set radial clearance range.

2. The low-noise three-screw pump as described in claim 1, characterized in that: The positioning sleeve (105) is provided with a first small stepped cylinder (1052) and a second large stepped cylinder (1053), the diameters of the first small stepped cylinder (1052) and the second large stepped cylinder (1053) are both larger than the main body diameter of the positioning sleeve (105). The first small stepped cylinder (1052) and the second large stepped cylinder (1053) are sandwiched to form the annular limiting groove (1051).

3. A low-noise three-screw pump as described in claim 2, characterized in that: The front end of the new driven screw (104) is also provided with a cylindrical stepped section (1042), the diameter of which is equal to the diameter of the cylindrical guide section (1041); The cylindrical stepped section (1042) and the cylindrical guide section (1041) are sandwiched to form an annular groove (1043), and the first small stepped cylinder (1052) can be rotatably embedded in the annular groove (1043).

4. A low-noise three-screw pump as described in claim 3, characterized in that: The low-noise three-screw pump also includes a positioning pin (107) that passes radially through the positioning sleeve (105) and is fixed to the new active screw (103).

5. A low-noise three-screw pump as described in claim 2, characterized in that: The low-noise three-screw pump also includes a bearing (7) and a new front cover (101). The inner ring of the bearing (7) is fitted onto the main body diameter portion in front of the second large stepped cylinder (1053) of the positioning sleeve (105). The outer ring of the bearing (7) is clamped circumferentially by the new front cover (101).

6. A low-noise three-screw pump as described in claim 5, characterized in that: The new front cover (101) is connected to the side of the pump body (1) and the side of the bushing (4) by screws and / or bolts.

7. A low-noise three-screw pump as described in claim 1, characterized in that: The tapered oil guide surface (10411) has a taper of 1:

20.

8. A low-noise three-screw pump as described in claim 1, characterized in that: The low-noise three-screw pump also includes a new sealing gland (102), which is fitted onto the smooth section of the new active screw (103) above the positioning sleeve (105) by means of a mechanical seal (9); the new sealing gland (102) is provided with a rearward abutment ring, which abuts against the front end face of the outer ring of the bearing (7); the rear end of the moving ring of the mechanical seal (9) abuts against the front end face of the positioning sleeve (105).

9. A low-noise three-screw pump as described in claim 6, characterized in that: An O-ring (106) is provided at the clearance mating surface (15) between the pump body (1) and the bushing (4) for sealing.

10. A marine hydraulic system, characterized in that: The ship's hydraulic system is equipped with a low-noise three-screw pump as described in any one of claims 1 to 9.

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