Marine engine direct-drive sea water pump

Abstract

The utility model discloses a marine engine direct load seawater pump, aims at solving the problem of traditional seawater pump structure loose, low transmission precision, weak corrosion resistance and high maintenance cost. The seawater pump adopts the integration casting structure of working area and transmission area, is directly integrated in the rear end of engine, and the independent support is saved, and the space occupation is reduced compared with the split type structure. The core component selects the corrosion -resistant material, the pump body is brass, the pump shaft is stainless steel, the sealing element is fluorine glue, the impeller is the seawater -resistant rubber, and the multiple sealing of cooperation mechanical seal, oil seal, O type ring blocks the seawater corrosion path. The transmission system adopts the multistage precision straight gear direct connection engine gear system. The shafting support adopts the self -sealed deep groove ball bearing, and the regular greasing is not needed, and the vulnerable part can be replaced quickly through the rear end cover plate. The compact engine room environment of adaptation ship and high -low speed complex working condition, improve the stability and maintenance -free of cooling system.

Description

Technical Field

[0001] This utility model relates to the field of marine power equipment, specifically to a marine engine direct-load seawater pump. Background Technology

[0002] Marine engine seawater pumps are core equipment in the cooling cycle of a ship's power system. Their main function is to draw seawater from pipelines or gates, pressurize it, and deliver it to heat exchange components such as engine oil coolers and freshwater coolers to remove the heat generated during engine operation. This ensures that the engine oil and coolant temperatures are maintained within safe ranges, directly affecting the stability of the engine's power output and its service life. As ships develop towards larger sizes and higher power densities, engine room layouts are becoming increasingly compact. At the same time, the strong corrosiveness of seawater and the frequent switching between high and low speeds during ship navigation place higher demands on the structural integration, transmission precision, corrosion resistance, and ease of maintenance of seawater pumps.

[0003] However, existing marine engine seawater pumps still have some technical shortcomings in practical applications, making it difficult to fully adapt to the complex operating conditions of ships. These include:

[0004] (1) Loose structural layout and low space utilization. Most existing seawater pumps adopt a split design of "pump body-support", such as the elastic rubber impeller seawater pump disclosed in CN118257742A. The pump body needs to be additionally fixed and connected to a support to support the drive structure, resulting in a larger overall axial dimension. At the same time, the seawater pump needs to be installed on the side of the engine through an independent support, rather than being directly integrated with the engine. This not only occupies more engine room space, but also requires additional design of pipelines to connect to the engine cooling system, increasing the complexity of system assembly and the risk of leakage.

[0005] (2) Insufficient transmission accuracy and poor adaptability to high and low speed conditions. The mainstream marine seawater pumps currently use belt pulley drives, such as the marine engine seawater pump proposed in CN215566660U, which adjusts the transmission ratio through double-diameter pulley grooves to accommodate both high and low speed conditions. However, belt drives have inherent defects. On the one hand, slippage is likely to occur between the belt and the pulley groove, resulting in low speed control accuracy. Under high-speed conditions, overspeed can easily exacerbate water seal wear, while under low-speed conditions, insufficient speed may lead to low cooling water flow rate, causing excessively high engine oil and fresh water temperatures. On the other hand, the belt is in a humid and high-temperature engine room environment for a long time, which can easily lead to aging and cracking. It needs to be disassembled and replaced regularly, which not only increases maintenance time and costs, but may also cause the cooling system to be interrupted due to sudden belt failure, posing a hidden danger to the safe operation of the engine.

[0006] (3) Weak corrosion resistance and short service life. Seawater contains high concentrations of chloride ions, which have a strong corrosive effect on metal parts and seals. Some existing seawater pumps have shortcomings in material selection. For example, some pump bodies are made of ordinary cast iron or carbon steel, which are prone to rust and wear of the inner wall when in contact with seawater for a long time, resulting in a decrease in the sealing performance of the compression chamber and a reduction in flow rate and head. Some seals are made of ordinary nitrile rubber, which has a narrow temperature range of seawater resistance and is easily corroded and aged by chloride ions.

[0007] In summary, existing marine engine seawater pumps suffer from low structural integration, poor transmission accuracy, weak corrosion resistance, and high maintenance costs, failing to fully meet the demands of modern ships for compact, high-precision, long-life, and low-maintenance cooling systems. Therefore, a new type of marine engine seawater pump is needed. Utility Model Content

[0008] To address the aforementioned shortcomings of existing technologies, this utility model designs an integrated, direct-load, high-precision transmission, and highly corrosion-resistant marine engine seawater pump. Through structural innovation, transmission system upgrades, enhanced corrosion-resistant design, and optimized maintenance system, it specifically solves the problems of traditional seawater pumps under complex ship operating conditions.

[0009] This utility model relates to a direct-load seawater pump for marine engines, comprising a pump body, a shaft assembly, an impeller, a sealing system, a transmission system, a bearing system, and a cover plate;

[0010] The front end of the pump body is sealed and fitted to the engine crankcase, and the rear end of the pump body is sealed and connected via the cover plate.

[0011] The shaft assembly includes a pump shaft and a retaining ring for the bore. The pump shaft has a stepped positioning groove on its outer circumference. One end of the pump shaft is interference-fitted with the impeller, and the other end is sequentially assembled with the transmission system and the bearing system. The retaining ring for the bore is installed in the positioning groove of the pump shaft near the transmission system and axially abuts against the transmission system and the bearing system.

[0012] The impeller is located within the working area of ​​the pump body and rotates synchronously with the pump shaft.

[0013] The transmission system includes a gear that directly meshes with the rear gear train of the engine to transmit power, and the gear is circumferentially fixed and axially fastened to the pump shaft;

[0014] The bearing system includes a drive end bearing mounted on the drive end of the pump shaft and an impeller end bearing mounted on the impeller end of the pump shaft.

[0015] Preferably, the pump body is made of brass, and the inner wall surface of the working area of ​​the pump body is smooth; the working area is divided into a low-pressure section and a high-pressure section; the low-pressure section includes a water inlet on the side of the pump body, and the high-pressure section includes a water outlet of the pump body.

[0016] Preferably, the impeller includes a cylindrical wheel body and multiple elastic blades, the blades being equidistantly distributed along the circumference of the wheel body, and the blades gradually thinning radially outward from the root.

[0017] Preferably, the cover plate is fixed to the pump body end face by hexagonal bolts coated with fastening adhesive.

[0018] Preferably, the sealing system includes a mechanical seal, an oil seal, and an end cap seal. The mechanical seal is mounted on the pump shaft near the impeller to seal the seawater and air in the working area. The oil seal is mounted on the pump shaft near the transmission system to seal the bearings in the transmission area and the engine oil area. The end cap seal includes a front O-ring for sealing the engine oil and air inside the engine, and a rear O-ring located at the rear end of the pump body for sealing the seawater and air.

[0019] Preferably, the pump body has a concealed flow channel at the bottom to discharge the small amount of leaked liquid from the mechanical seal.

[0020] Preferably, the gear has 30 teeth and a normal module of 3; the spur gear has a keyway at its center, and is circumferentially fixed by a flat key engaging with the keyway of the pump shaft; the gear is axially fastened to a washer by a hexagonal nut.

[0021] Preferably, the transmission end bearing and the impeller end bearing are self-sealing deep groove ball bearings.

[0022] Preferably, the retaining ring of the hole simultaneously abuts against the end face of the spur gear and the end face of the transmission end bearing.

[0023] The ship's engine-mounted seawater pump has the following advantages:

[0024] (1) Improved spatial integration, simplified structure, and simplified pipeline connection. The working area and transmission area are integrated into one casting design and directly integrated into the rear end of the engine, eliminating the need for the independent bracket required by traditional seawater pumps and reducing space occupation compared to the split structure. Because it directly connects to the engine cooling system, there is no need to design additional long-distance connecting pipelines, reducing the complexity of system assembly, reducing the number of pipeline interfaces, shortening the seawater delivery path, and improving the cooling response speed.

[0025] (2) Improved transmission accuracy and stability, adaptable to high and low speed conditions. Gear transmission replaces belt transmission, and a 7-stage precision spur gear directly connects to the engine gear system. Under high-speed conditions, the pump shaft speed can be precisely controlled, avoiding water seal wear caused by overspeed. Under low-speed conditions, there is no need to rely on belt pulley switching; the output speed can be stabilized through the gear transmission ratio, ensuring that the cooling water flow rate meets the standard and preventing excessively high engine oil and fresh water temperatures. The meshing noise of gear transmission is lower than that of belt transmission, and the maintenance cycle of the transmission system is extended.

[0026] (3) Corrosion-resistant design throughout the entire process. The pump body is made of H62 brass; the pump shaft is made of stainless steel; the impeller is made of seawater-resistant rubber; and all seals are made of fluororubber. Multiple sealing barriers are set up, including a seawater-side mechanical seal, an oil-side fluororubber seal, and O-rings at the front and rear ends, to block the channels for seawater to enter the shaft system and for oil to leak into the seawater chamber.

[0027] This utility model relates to a marine engine direct-load seawater pump, which features a compact structure, good stability, and reliable durability. Attached Figure Description

[0028] Figure 1 This is a cross-sectional view of an embodiment of the present utility model;

[0029] Figure 2 This is a perspective view of an embodiment of the present utility model.

[0030] Explanation of reference numerals in the attached diagram: 1-Hexagonal nut; 2-Washer; 3-Gear; 4-Oil seal; 5-Retaining ring for the hole; 6-Pump shaft; 7-Pump body; 8-Impeller; 9-Rear end O-ring; 10-Cover plate; 11-Hexagonal bolt; 12-Mechanical seal; 13-Drive end bearing; 14-Front end O-ring; 15-Impeller end bearing; 16-Inlet; 17-Outlet. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] The marine engine direct-load seawater pump disclosed in this embodiment solves the problems of loose layout, low transmission accuracy, weak corrosion resistance, and high maintenance costs of traditional seawater pumps through integrated design of the working area and transmission area, high-precision transmission matching, and full-link corrosion-resistant protection. It achieves tight integration with the engine and is suitable for the compact engine room environment and complex high- and low-speed operating conditions of ships. Figure 1 , Figure 2 As shown below, the specific structure and the connection relationships between each part are described in detail.

[0033] (a) Overall structure.

[0034] This utility model seawater pump adopts an integrated casting structure, which can be bolted to the rear end of the engine, eliminating the need for independent brackets in traditional split structures. This reduces the overall axial dimension and improves space utilization. The core load-bearing component is the pump body 7, which can be made entirely of H62 brass, possessing excellent seawater corrosion resistance and casting processability, thus preventing rusting of the cavity caused by long-term seawater erosion. The pump body 7 is precision-machined internally to ensure that the assembly gaps of each component are within a controlled range, reducing the risk of operational vibration and media leakage.

[0035] The front end of the pump body 7 is sealed to the engine crankcase via a fluororubber O-ring 14, forming a primary seal between the pump body and the engine. The rear end of the pump body 7 is sealed to the rear cover plate 10 via a fluororubber O-ring 9. The cover plate 10 can be made of stainless steel and is fixed to the end face of the pump body 7 with M6×10 hex bolts 11. Before assembly, the bolts 11 need to be coated with Loctite adhesive to prevent loosening caused by ship turbulence, ultimately forming a closed structure between the engine, pump body, and cover plate.

[0036] (II) Components. The seawater pump in this embodiment includes the following parts:

[0037] (1) Shaft assembly. It is the key to the power transmission of the seawater pump, including the pump shaft 6 and the retaining ring 5 for the bore.

[0038] The pump shaft 6 is made of stainless steel, which has better corrosion resistance than ordinary carbon steel. It has stepped positioning grooves machined axially, which are used to assemble the impeller 8, mechanical seal 12, transmission end bearing 13 and impeller end bearing 15, and gear 3, respectively, to achieve precise positioning of each component. The two ends of the pump shaft 6 extend out of the transmission area and working area of ​​the pump body 7, respectively, to ensure that power is transmitted from the transmission end to the working end.

[0039] Connection with impeller 8: The end of pump shaft 6 near the working area is interference-fitted with the inner hole of impeller 8. The interference is controlled at 0.02-0.03mm to ensure that impeller 8 rotates synchronously with pump shaft 6 without relative slippage, thus avoiding flow attenuation caused by slippage.

[0040] The retaining ring 5 for the bore is of model 52×1.8 and made of 65Mn spring steel. It is installed in the positioning groove of the pump shaft 6 near the transmission area and is axially close to the end face of the gear 3 and the transmission end bearing 13. It is used to limit the axial displacement of the gear 3 and the transmission end bearing 13 and avoid component collision caused by shaft movement when the ship is rocking.

[0041] (2) The impeller 8 is the actuator for the "water intake-pressurization-drainage" of seawater. Its cooperation with the working chamber of the pump body 7 and the pump shaft 6 directly determines the conveying efficiency.

[0042] Impeller 8 structure: Made of seawater-resistant rubber, the impeller consists of a body and six elastic blades. The body is cylindrical, with an inner bore that is interference-fitted with the pump shaft 6. The blades are evenly distributed around the circumference of the impeller, with a blade root thickness of 8mm, gradually decreasing to 3mm radially outward. This gradual thickness design enhances the blade's deformation capability, allowing it to adapt to the elliptical contour of the pump body 7's working chamber, always maintaining contact with the chamber wall and reducing seawater backflow leakage.

[0043] Adaptation to the working chamber of pump body 7: The inner wall of the working area (impeller chamber) of pump body 7 is precision ground with a surface roughness Ra≤0.8μm. The chamber is divided into a "low-pressure section" and a "high-pressure section": The low-pressure section is located below the axis of impeller 8 and corresponds to the inlet 16 (diameter φ32mm) on the side of pump body 7. The high-pressure section corresponds to the outlet 17 on the other side of pump body 7. When impeller 8 rotates, the blades open in the low-pressure section, the volume increases and a negative pressure is formed. Seawater is drawn in through inlet 16, and is compressed and pressurized by the chamber wall in the high-pressure section. Finally, it is discharged from outlet 17, completing the transportation cycle.

[0044] (3) Sealing system. The sealing system consists of a three-tiered structure: “seawater side seal”, “oil side seal”, and “end cover seal”. Its function is to prevent seawater from entering the shaft system and oil from leaking into the seawater cavity.

[0045] The seawater side seal, also known as mechanical seal 12, adopts the MG-20 type mechanical seal, with sealing rings made of fluororubber or silicone. Mechanical seal 12 is installed in the stepped groove of the pump shaft 6 near the impeller 8. Its stationary ring is interference-fitted with the inner wall of the working area of ​​the pump body 7, and its rotating ring is interference-fitted with the pump shaft 6, forming a radial seal between the pump shaft and the pump body. It is mainly used to seal the seawater and air in the working area, preventing dust and seawater leakage; and to seal the bearings and air in the transmission area, serving a dustproof function.

[0046] The oil-side seal, also known as oil seal 4, is made of fluororubber or silicone and measures 52×25×8. It is installed in the stepped groove of the pump shaft 6 near the gear 3, axially fitting with the retaining ring 5. The lip of oil seal 4 faces the gear cavity (engine oil area), primarily sealing the transmission bearing and engine oil area to prevent engine oil from flowing into the transmission.

[0047] The end cap seal includes a front O-ring 14 and a rear O-ring 9, made of materials such as fluororubber or silicone. The front O-ring 14 is embedded in the groove of the mating surface between the pump body 7 and the engine crankcase, mainly used to seal the engine oil and air inside; the rear O-ring 9 is embedded in the groove of the mating surface between the pump body 7 and the cover plate 10, mainly used to seal seawater and air, forming a double primary seal at both ends. In addition, a concealed flow channel is designed at the bottom of the pump body 7. If a small amount of leakage occurs in the mechanical seal 12, the leaked liquid can be discharged to the outside of the pump body 7 through this flow channel, avoiding accumulation and corrosion of the shaft system.

[0048] (4) The transmission system adopts a gear 3 direct connection method to replace the traditional belt drive, which is compatible with the engine rear gear system to ensure the speed accuracy under high and low speed conditions.

[0049] Gear 3 parameters and structure: Model 3M30Z, 30 teeth, normal module 3, addendum circle diameter φ96.86-φ97.06mm, normal pressure angle 20°, helix angle 0°, accuracy class conforms to DIN3960-DIN3963 grade 7. Gear 3 has a keyway (6×10mm) machined in the center, corresponding to the keyway of pump shaft 6, and is circumferentially fixed by a flat key.

[0050] Connection with pump shaft 6: Gear 3 is sleeved on the drive end step of pump shaft 6 and is axially fastened to washer 2 by M16×1.5 left-hand hexagonal nut 1. Washer 2 is placed between the end face of gear 3 and nut 1. After nut 1 is tightened, it ensures that gear 3 has no axial movement, so as to realize the zero-slip transmission of power from engine gear system to pump shaft 6.

[0051] Transmission advantages: Compared with traditional double-groove belt pulley transmission, this gear 3 transmission has reduced meshing noise, improved speed control accuracy, and extended maintenance cycle.

[0052] (5) The bearing system provides radial and axial support for the shaft system. It adopts self-sealing deep groove ball bearings, which do not require regular greaseing and are suitable for the inconvenient working conditions of ship maintenance.

[0053] Bearing configuration and installation: Bearing 13 of model 6204 is used at the drive end (near gear 3), and bearing 15 of model 6205 is used at the impeller end (near mechanical seal 12). Both bearings are 2RS self-sealing structures with built-in rubber seals to prevent seawater vapor, engine oil and impurities from entering the bearing.

[0054] Connection with pump shaft 6 and pump body 7: The inner rings of bearings 13 and 15 are interference-fitted with pump shaft 6 to ensure that the bearings rotate synchronously with pump shaft 6. The outer rings of bearings 13 and 15 are transition-fitted with the bearing holes of pump body 7. The axial preload is controlled during assembly to ensure that the radial runout of the shaft system is small during operation and to avoid seal failure due to vibration.

[0055] (III) Work Process. The work process of the seawater pump in this embodiment revolves around power transmission, seawater transportation, and sealing protection. The coordination relationship of each component is as follows:

[0056] (1) Power transmission: The rear gear system of the engine meshes with the gear 3 of the seawater pump. When the engine is running, it drives the gear 3 to rotate. The gear 3 transmits power to the pump shaft 6 through a flat key. The pump shaft 6 drives the impeller 8 to rotate synchronously. The transmission ratio is 1:1.2. The speed of the impeller 8 is precisely matched with the speed of the engine gear system.

[0057] (2) Seawater transport: When the impeller 8 rotates in the working chamber of the pump body 7, the elastic blades adapt to the changes in the chamber shape. When the blades enter the low-pressure section (below the axis), the blades open, the volume between adjacent blades increases to form a negative pressure, and seawater is drawn in through the inlet 16. When the blades rotate to the high-pressure section (above the axis), they are squeezed and contracted by the chamber wall, the volume decreases and the seawater is pressurized, and finally transported to heat exchange components such as engine oil cooler and freshwater cooler through the outlet 17.

[0058] (3) Sealing protection: Mechanical seal 12 prevents seawater from entering the intermediate air chamber from the working chamber, oil seal 4 prevents engine oil from leaking from the gear chamber to the air chamber, and front O-ring 14 and rear O-ring 9 seal the gap between pump body 7 and engine and cover plate 10. If mechanical seal 12 leaks slightly, the leaked liquid can be discharged through the hidden flow channel at the bottom of pump body 7 to avoid corrosion of shaft system and bearing.

[0059] This embodiment achieves the requirements of compact integration, precise transmission, corrosion resistance, durability, and maintenance-free operation of seawater pumps through precise connection and collaborative design of various components, thus meeting the high-performance requirements of modern marine engine cooling systems.

[0060] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A marine engine direct-load seawater pump, characterized in that, Includes pump body (7), shaft assembly, impeller (8), sealing system, transmission system, bearing system and cover plate (10); The front end of the pump body (7) is sealed and fitted to the engine crankcase, and the rear end of the pump body (7) is sealed and connected through the cover plate (10). The shaft assembly includes a pump shaft (6) and a retaining ring (5) for the bore. The pump shaft (6) has a stepped positioning groove on its outer periphery. One end of the pump shaft (6) is interference-fitted with the impeller (8), and the other end is sequentially equipped with the transmission system and the bearing system. The retaining ring (5) for the bore is installed in the positioning groove of the pump shaft (6) near the transmission system and axially abuts against the transmission system and the bearing system. The impeller (8) is located in the working area of ​​the pump body (7) and rotates synchronously with the pump shaft (6); The transmission system includes a gear (3) that directly meshes with the rear gear train of the engine to transmit power. The gear (3) is circumferentially fixed and axially fastened to the pump shaft (6). The bearing system includes a drive end bearing (13) mounted on the drive end of the pump shaft (6) and an impeller end bearing (15) mounted on the impeller end of the pump shaft (6).

2. The marine engine direct-load seawater pump according to claim 1, characterized in that, The pump body (7) is made of brass and the inner wall surface of the working area of ​​the pump body (7) is smooth. The working area is divided into a low-pressure section and a high-pressure section. The low-pressure section includes a water inlet (16) on the side of the pump body (7) and the high-pressure section includes a water outlet (17) of the pump body (7).

3. The marine engine direct-load seawater pump according to claim 1, characterized in that, The impeller (8) includes a cylindrical wheel body and multiple elastic blades. The blades are equidistantly distributed along the circumference of the wheel body, and the blades gradually thin outward from the root.

4. The marine engine direct-load seawater pump according to claim 1, characterized in that, The cover plate (10) is fixed to the end face of the pump body (7) by hexagonal bolts (11) coated with fastening adhesive.

5. The marine engine direct-load seawater pump according to claim 1, characterized in that, It also includes the sealing system, which includes a mechanical seal (12), an oil seal (4) and an end cap seal. The mechanical seal (12) is mounted on the pump shaft (6) near the impeller (8) to seal the seawater and air in the working area. The oil seal (4) is mounted on the pump shaft (6) near the transmission system to seal the bearings in the transmission area and the engine oil area. The end cap seal includes a front O-ring (14) for sealing the engine oil and air inside the engine, and a rear O-ring (9) located at the rear end of the pump body (7) for sealing the seawater and air.

6. The marine engine direct-load seawater pump according to claim 1, characterized in that, The pump body (7) has a concealed flow channel at the bottom for discharging a small amount of leaked liquid from the mechanical seal (12).

7. The marine engine direct-load seawater pump according to claim 1, characterized in that, The gear (3) has 30 teeth and a normal module of 3; the spur gear (3) has a keyway at its center, which is used to fix the gear circumferentially by engaging with the keyway of the pump shaft (6) via a flat key; the gear (3) is axially fastened to the gasket (2) by a hexagonal nut (1).

8. The marine engine direct-load seawater pump according to claim 1, characterized in that, The transmission end bearing (13) and the impeller end bearing (15) are self-sealing deep groove ball bearings.

9. The marine engine direct-load seawater pump according to claim 3, characterized in that, The retaining ring (5) of the hole simultaneously abuts against the end face of the spur gear (3) and the end face of the transmission end bearing (13) in the axial direction.

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