Device for maintaining main bearing cover in high-power marine diesel engine room

Abstract

The utility model provides a device for maintaining a main bearing cover in a high-power marine diesel engine cabin, and belongs to the technical field of marine diesel engine maintenance. After the combined tool is designed, a triangular plate type complete machine lifting appliance capable of lifting a complete machine in a narrow space in a cabin, a four-point supporting tool for fixing a diesel engine, a device for disassembling and assembling an oil pan and protecting cleanliness, and a machine body opening device for disassembling and assembling a main bearing cover can be realized; the problems that when the main bearing cover is maintained in a cabin, the space is narrow, a ship shakes and is unstable in water, and the cleanliness is not high, so that the assembling technical difficulty of the main bearing cover is large are solved. Based on the device, a set of method for maintaining the main bearing cover in the cabin is formed, and the technical difficulty of maintaining the main bearing cover in the diesel engine cabin is effectively solved.

Description

Technical Field

[0001] This utility model belongs to the field of marine diesel engine maintenance technology, specifically relating to a device for maintaining the main bearing cover inside the compartment of a high-power marine diesel engine. Background Technology

[0002] The main bearing cap is one of the key components of a marine diesel engine. It is installed on the main bearing support plate of the engine hull and serves as half of the main bearing housing. After being assembled with the engine hull, it is machined to form a high-precision main bearing bore that allows the crankshaft to rotate.

[0003] After a certain type of high-power marine diesel engine 1 (5.5m long × 1.8m wide × 2.9m high, a V-type 20-cylinder engine with 11 main bearing caps) was delivered to the user, it was discovered that the strength of the front and rear main bearing caps (KS, KGS) (360mm wide, 10kg weight) did not meet the requirements of the drawings. Long-term operation would lead to deformation and loosening, which could easily cause serious quality accidents such as bearing failure and shaft seizure, resulting in engine damage and loss of life. Therefore, it is urgent to carry out main bearing cap repair work in the confined space of the engine room 3 (see...). Figure 1-3 Analysis revealed the following challenges in repairing the main bearing cover inside the cabin:

[0004] 1) The main bearing cap 1-3 is the first part assembled on the diesel engine and is an integrally machined part with the engine body 1-1. It is the most basic single-fixed part of the diesel engine. Normal operation requires breaking open the compartment 3-3 to retrieve the diesel engine and return it to the factory for repair. The costs of breaking open the compartment, transporting the diesel engine back to the factory, and repairing it are huge, amounting to tens of millions of yuan in repair costs.

[0005] 2) The diesel engine is located in the bottom compartment of the hull. To remove the entire engine from the compartment, the relevant compartments at the top need to be cut. The diesel engine is lifted out by a large-tonnage crane and placed inside the soundproof enclosure 2 in the engine room (maintenance space of about 0.5m). The oil, water, gas and electricity systems are involved in the complex engineering, which involves a huge amount of work, complicated operation and high difficulty.

[0006] 3) Conventional factory repair methods require the complete disassembly of the diesel engine (which is assembled from more than 10,000 parts), disassembling the engine body 1-1, replacing the new main bearing cover 1-3, reassembling the diesel engine 1, and returning it to the ship's hold after passing bench testing, centering, and restoring the various systems in the engine room. This requires a large number of disassembly and assembly tools and repair space. However, the space inside the hold is small, making construction difficult and cleanliness control challenging. Therefore, conventional whole-machine disassembly repair methods cannot be used inside the hold.

[0007] 4) The diesel engine is heavy (greater than 20 tons). The lifting beam type whole machine hoisting tool (3m lifting space) is equipped with this model. The cabin space is small (1.5m lifting space), so this type of hoisting tool cannot be installed and used, making it difficult to lift the diesel engine.

[0008] 5) The main bearing cover 1-3 and the machine body 1-1 are interference fit (interference 0.01-0.06mm). The machine body needs to be opened (0.1-0.5mm) during disassembly and assembly. The main bearing cover is fastened to the machine body 1-1 by a set of main bearing bolts 1-4 and a set of transverse bolts 1-6. The main bearing bolts are high-strength bolts (elongation 1-1.05mm). The transverse bolts are tightened by torque plus angle. The tightening requirements are high and the assembly is difficult.

[0009] 6) During normal maintenance, the machine body 1-1 should be bored to fit the new main bearing cover, ensuring that the coaxiality of adjacent sections is ≤0.04mm and the coaxiality of each section is ≤0.2mm. Before installing the crankshaft, a trial installation of the bearing cover with bearing shell should be performed, and the diameter of the bearing shell bore and the lateral ellipticity should be ≤0.07mm to ensure that there is a suitable oil clearance with the crankshaft to meet the requirements of crankshaft lubrication and heat dissipation. The high assembly precision leads to greater maintenance difficulty.

[0010] Based on the research, the following three relevant repair solutions exist:

[0011] Option 1: After breaching the hull and retrieving the diesel engine, return it to the factory for main bearing cover repair. The factory repair method requires completely disassembling the diesel engine, removing the engine body, installing a new main bearing cover, reassembling the diesel engine, conducting bench tests to meet standards, returning it to the ship's hold for positioning, alignment, restoration of various systems in the engine room, and welding repairs to breach the hull. This requires a large number of disassembly and assembly tools and a repair site. Currently, there are about 20 cases of this type of engine being returned to the factory for repair and replacement of main bearing covers of various grades.

[0012] Option 2: A method for replacing the main engine crankshaft of a ship, including setting up the lifting point, confirming the lifting position, opening the process hole, pre-setting the bracket, removing accessories, lifting the crankshaft and the frame simultaneously, lowering the crankshaft to the pre-set bracket, translating the crankshaft, lifting the crankshaft again, moving the crankshaft forward, slowly turning the crankshaft, the crankshaft exiting the process hole, the new crankshaft entering the cabin in reverse process, and the installation and positioning process.

[0013] Option 3: A method and apparatus for assembling a crankshaft with the engine body upright. The assembly method involves fixing the crankshaft, hoisting the engine body downwards, and pre-positioning it with the crankshaft; then fixing the engine body again, raising the crankshaft, and finally positioning and installing it with the engine body. This method is widely used in the crankshaft assembly process during the production of medium- and high-speed, high-power diesel engines.

[0014] The shortcomings of the above three solutions are:

[0015] Option 1: This option is applicable to diesel engines where all main bearing caps need to be replaced and repaired. The amount of work involved in repairing damaged parts and returning them to the factory is huge, with the repair cost of each engine reaching tens of millions of yuan. The repair scenarios change frequently, involving many projects and units, and the impact of the incident is wide-ranging, with various uncontrollable potential risks.

[0016] Option 2: This option is applicable to crankshaft replacement inside the crankshaft compartment. It focuses on the hoisting method of the whole engine and crankshaft inside the compartment. The space inside the compartment is sufficient and the hoisting is simple. However, it fails to explain the technical difficulties of the main bearing cap repair mentioned above. The repair process of the diesel engine itself is unclear. Overall, the option is relatively crude.

[0017] Option 3: This option is applicable to the normal installation of the crankshaft in diesel engines, focusing on a crankshaft installation scheme when the engine body is upright. It fails to explain the technical difficulties in the maintenance of the bearing cover, does not identify the complexity and difficulty of the maintenance inside the compartment, and cannot solve the technical difficulties in the maintenance of the main bearing cover involved in this case.

[0018] In summary, the repair of the main bearing cover inside the engine compartment of this type of diesel engine is complex, technically demanding, and difficult to perform. Existing repair procedures are all flawed and cannot effectively guide the inside-compartment repair of the main bearing cover of this type of diesel engine. To solve the aforementioned challenges of inside-compartment repair of the main bearing cover, reduce the difficulty and complexity of repair work, eliminate repair risks, significantly reduce repair costs, and control the impact of the incident, a completely new device and method for inside-compartment repair of the main bearing cover of high-power marine diesel engines needs to be designed. Utility Model Content

[0019] The technical problem solved by this utility model is to provide a device for repairing the main bearing cover in the engine room of a high-power marine diesel engine. The purpose of this utility model is to solve the problems of high technical difficulty in assembling the main bearing cover due to the small space in the engine room, the unstable swaying of the ship in the water, and the low cleanliness, so as to achieve efficient and high-quality repair of the diesel engine main bearing cover in the engine room.

[0020] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0021] An apparatus for repairing main bearing caps inside a high-power marine diesel engine compartment includes a combination tool for such repairs. This combination tool comprises a triangular-plate type engine lifting device, support fixtures, an oil pan disassembly and cleaning protection device, and a fuselage opening device. Two sets of the triangular-plate type engine lifting device are installed on the output end and free end of the diesel engine, respectively. The upper end of the triangular-plate type engine lifting device is securely connected to lifting points fixed to the three decks of the engine compartment via a manual hoist. Four sets of support fixtures are fixed at the four corners of the bottom of the diesel engine, which is being lifted a certain distance, to support it. The oil pan disassembly and cleaning protection device handles the disassembly and cleaning of the oil pan. The fuselage opening device is installed at the adjacent fuselage openings of the two main bearing caps at the output end and free end of the diesel engine and is used to open the fuselage.

[0022] Further defining the above technical solution, the triangular plate type hoist includes a triangular hoist plate. The two lower corners of the triangular hoist plate are each connected to a special steel rope via a D-type shackle 1. The lower end of the special steel rope is used to connect and secure it to the lifting eye bolt on the diesel engine. The upper corner of the triangular hoist plate is connected to a manual hoist via a D-type shackle 2. The manual hoist is securely connected to the hoisting point of the whole machine welded to the three-layer deck.

[0023] As a further limitation of the above technical solution, the distance between the two special steel ropes at the bottom of the triangular lifting plate is determined according to the lifting distance L1 of the lifting eye bolt on the diesel engine.

[0024] Further defining the above technical solution, the structure of the supporting fixture includes two vertical plates symmetrically fixed between the bottom plate and the top plate, and a reinforcing plate fixed between the two vertical plates; the bottom plate is used to be fastened to the I-beam on the diesel engine, and the top plate is used to be fastened to the support bracket on the diesel engine.

[0025] Further defining the above technical solution, the oil pan disassembly and cleanliness protection device includes a plastic sheet for laying on the oil pan, sleepers for padding under the oil pan, and wooden boards for laying on the I-beams at the output end and free end of the diesel engine as a maintenance work platform.

[0026] Further defining the above technical solution, the fuselage opening device includes a left-hand stud and a right-hand stud for supporting the opening on sides A and B of the fuselage, and an opening nut for threadedly connecting the left-hand stud and the right-hand stud.

[0027] Advantages of this utility model compared to the prior art:

[0028] 1. The modular tool provided in this solution for the maintenance of main bearing caps in the cabin is reasonably designed, uses inexpensive materials, is easy to manufacture, convenient to use, and has a high safety factor. It has high reference value for disassembly, lifting, cleaning and safety protection in the confined space of the cabin. It can be used in combination according to the maintenance conditions in the cabin and is suitable for various major maintenance operations in the cabin of marine high-power diesel engines. It is easy to promote.

[0029] 1) This modular tool has a reasonable structural design, uses inexpensive materials, is easy to manufacture, is convenient to use, and has a high safety factor. It can meet the safety requirements of lifting, disassembly, and protection when repairing the main bearing cover of the diesel engine in the cabin. Through combined application, it is suitable for various types of major maintenance operations of diesel engines in the cabin. It is easy to operate and has strong promotion potential.

[0030] 2) The triangular plate type integral lifting device has a simple structure and occupies little space (L2≤1.5m), making it easy to lift the entire machine in confined spaces within the cabin. The triangular lifting plate is preferably made of 45GB / T699 steel plate, with three lifting holes drilled for installing shackles. A 15t load test was conducted on the lifting plate. It has low material costs, low processing difficulty, convenient transportation and use, and is safe and reliable. It can be adjusted according to the center distance L1 of the diesel engine lifting eye bolts, making it highly adaptable.

[0031] 3) The 4-point support fixture for fixing the diesel engine is preferably made of 5 independent Q235A carbon steel plates, which are cut, processed and welded. The weld bevel is reserved, and the full-fusion electric arc welding is used. The structure has high strength and the welding is reliable. The upright plate can be adjusted according to the lifting height L3 to adapt to the diesel engine support at different heights and create an operating space that meets the needs of the main bearing cover maintenance.

[0032] 4) Used for oil pan disassembly and cleaning protection devices, made of low-cost materials such as wood and plastic, combined design to meet the needs of protection, hoisting and other operations, highly practical, easy to manufacture and select;

[0033] 5) Used for matching left and right threads of the body opening device during the disassembly and assembly of the main bearing cover. The left side is designed with a left-hand threaded connection, and the right side is designed with a right-hand threaded connection. The design is ingenious.

[0034] 2. This solution provides a method for repairing the main bearing cover of a high-power marine diesel engine inside the tank. After designing a combination tool for repairing the main bearing cover inside the tank, it can realize a triangular plate type lifting tool for lifting the whole machine in the narrow space inside the tank, a 4-point support tool for fixing the diesel engine, a device for disassembling and assembling the oil pan and cleaning protection, and a device for opening the hull and tightening bolts when disassembling and assembling the main bearing cover. It can solve the problems of the narrow space for repairing the main bearing cover inside the tank, the instability of the ship in the water, and the high technical difficulty of assembling the main bearing cover due to the low cleanliness.

[0035] 3. The method and process for repairing the main bearing cover inside the cabin in this plan is clear, reasonable, and easy to operate and implement. It avoids the massive project of cabin damage and diesel engine return to the factory for repair, reduces the difficulty and complexity of repair and construction, eliminates repair risks, significantly reduces repair costs, controls the scope of the impact of the event itself, and reduces repair costs from tens of millions to hundreds of thousands.

[0036] 4. The method and device for repairing the main bearing cover inside the cabin in this solution overcomes the technical difficulties of repairing the main bearing cover inside the cabin of a high-power marine diesel engine, and provides a brand-new method for repairing diesel engines with similar structures inside the cabin. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the diesel engine compartment structure of this utility model;

[0038] Figure 2This is a schematic diagram of the diesel engine structure in the engine compartment of this utility model, facing A.

[0039] Figure 3 This is a schematic diagram of the B-direction diesel engine structure inside the engine compartment of this utility model;

[0040] Figure 4 This is a schematic diagram of the main bearing cover for maintenance inside the engine compartment of this utility model.

[0041] Figure 5 This is a schematic diagram of the main bearing cover for maintenance inside the engine room of this utility model, shown in direction A′.

[0042] Figure 6 This is a schematic diagram of the main bearing cover for maintenance inside the engine room of this utility model, shown in direction B′.

[0043] Figure 7 This is a schematic diagram of the triangular plate type hoisting device in this utility model.

[0044] Figure 8 This is a schematic diagram of the support fixture in this utility model.

[0045] Figure 9 This is a schematic diagram of the fuselage spreading device in this utility model.

[0046] In the picture:

[0047] 1. Diesel Engine 1-1 Engine Body 1-2 Crankshaft 1-3 Main Bearing Cap 1-3 KS Output End Main Bearing Cap 1-3 KGS Free End Main Bearing Cap 1-4 Main Bearing Bolt 1-5 Main Bearing Round Nut 1-6 Transverse Bolt 1-7 Eye Bolt 1-8 Support Bracket 1-9 Rubber Vibration Isolator 1-10 I-beam 1-11 Oil Pan 1-12 Oil Pan Bolt 1-13 Hydraulic Coupling 1-14 Transmission Box

[0048] 2 boxes

[0049] 3. Engine Room 3-1. Lower Deck 3-2. Second Deck 3-3. Third Deck 4. Engine Lifting Equipment 4-1. Triangular Lifting Plate 4-2. D-Type Shackle 1 4-3. Special Steel Rope 4-4. D-Type Shackle 2

[0050] 5 Support fixtures 5-1 Base plate 5-2 Vertical plate 5-3 Reinforcing plate 5-4 Top plate

[0051] 6. Plastic sheeting 7. Sleepers 8. Wooden planks

[0052] 9. Machine body opening device; 9-1 Left-hand stud; 9-2 Opening nut; 9-3 Right-hand stud; 10. Manual hoist

[0053] 11. Overall lifting points 12. Lifting slings

[0054] L1 is the lifting distance between the eye bolts of the diesel engine.

[0055] L2 is the distance from the diesel engine to the third deck.

[0056] L3 is the lifting height of the diesel engine.

[0057] α is the tilt angle when the oil pan is disassembled or assembled. Detailed Implementation

[0058] 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 scope of protection of the present utility model.

[0059] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover a 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.

[0060] Please see Figure 1-9 The embodiments of this utility model are described in detail below.

[0061] Example 1: A device for repairing the main bearing cover inside the tank of a high-power marine diesel engine, including a combination tool for repairing the main bearing cover inside the tank. The combination tool includes a triangular plate type whole machine lifting tool 4, a support fixture 5, an oil pan disassembly and cleaning protection device, and a fuselage opening device 9.

[0062] The triangular plate type whole machine lifting tool 4 is provided in two sets and is used to be installed on the output end KS and the free end KGS of the diesel engine 1 respectively. The upper end of the triangular plate type whole machine lifting tool 4 is fastened to the whole machine lifting point 11 fixed on the third deck 3-3 of the engine room 3 through a manual hoist 10. The triangular plate type whole machine lifting tool 4 can lift the whole machine in the narrow space inside the cabin.

[0063] The support fixture 5 is provided in four sets and is fixed at the four corners of the bottom of the diesel engine 1, which is being lifted a certain distance, to support the diesel engine 1.

[0064] The oil pan disassembly and cleanliness protection device is used for the disassembly and cleanliness protection of oil pans 1-11;

[0065] The fuselage opening device 9 is installed at the opening of the adjacent fuselage 1-1 of the two main bearing covers 1-3 at the diesel engine output end and free end, and is used to open the fuselage 1-1.

[0066] In one specific embodiment: see Figure 7 As shown, the triangular plate type hoist 4 includes a triangular hoist 4-1. The two lower corners of the triangular hoist 4-1 are connected to a special steel rope 4-3 via D-type shackles 14-2. The lower end of the special steel rope 4-3 is used to connect and fasten to the lifting eye bolt 1-7 on the diesel engine 1. The upper corner of the triangular hoist 4-1 is connected to a manual hoist 10 via a D-type shackle 24-4. The manual hoist 10 is fastened to the hoisting point 11 welded to the third deck 3-3.

[0067] Preferably, the distance between the two special steel ropes 4-3 at the lower part of the triangular lifting plate 4-1 is determined according to the lifting distance L1 of the lifting eye bolt 1-7 on the diesel engine.

[0068] In one specific embodiment: see Figure 8 As shown, the structure of the support fixture 5 includes two vertical plates 5-2 symmetrically fixed between the base plate 5-1 and the top plate 5-4, and a reinforcing plate 5-3 fixed between the two vertical plates 5-2; the base plate 5-1 is used to be fastened to the I-beam 1-10 on the diesel engine 1, and the top plate 5-4 is used to be fastened to the support bracket 1-8 on the diesel engine 1.

[0069] In this embodiment, the fastening bolts of the rubber vibration isolator 1-9 on the diesel engine 1 to the support bracket 1-8 and the I-beam 1-10 are removed. The lifting height L3 of the diesel engine 1 should be greater than 800mm. The four support fixtures 5 are fixed between the support bracket 1-8 and the I-beam 1-10 using machine bolts.

[0070] In one specific embodiment: see Figure 4 As shown, the oil pan disassembly and cleaning protection device includes a plastic sheet 6 for laying on the oil pan 1-11, a sleeper 7 for padding under the oil pan 1-11, and a wooden board 8 for laying on the I-beam 1-10 at the output end and free end of the diesel engine 1 as a maintenance work platform.

[0071] In this embodiment, two sets of 1t manual hoists are installed on the crossbeam frame of the box body 2. Two 1t slings 12 are used to disassemble and assemble the oil pan 1-11. Two sleepers 7 are placed under the oil pan 1-11. A plastic sheet 6 is laid on the oil pan for cleanliness protection. Wooden boards 8 are laid on the I-beams 1-10 at the output end KS and the free end KGS of the diesel engine 1 to serve as maintenance platforms for the operator.

[0072] In one specific embodiment: see Figure 9As shown, the fuselage opening device 9 includes a left-hand stud 9-1 and a right-hand stud 9-3 for supporting the openings on the A and B sides of the fuselage 1-1, and an opening nut 9-2 that is threadedly connected to the left-hand stud 9-1 and the right-hand stud 9-3.

[0073] In this embodiment, one hydraulic pump with two hydraulic tensioners is used and installed on the main bearing round nut 1-5. Pressure is applied to remove it from the main bearing bolt 1-4. A regular torque wrench is used to remove the transverse bolt 1-6 from the main bearing cover 1-3. The machine body opening device 9 is installed at the opening of the adjacent machine body 1-1 of the main bearing covers 1-3KS and 1-3KGS, which can open the machine body 1-1.

[0074] The combined tool in this embodiment has the following characteristics:

[0075] 1) The modular tool has a reasonable structural design, uses inexpensive materials, is easy to manufacture, is convenient to use, and has a high safety factor. It can meet the safety requirements of lifting, disassembly, and protection when repairing the main bearing cover of the diesel engine in the cabin. Through combined application, it is applicable to various types of major maintenance operations of diesel engines in the cabin. It is easy to operate and has strong promotion potential.

[0076] 2) The triangular plate type integral lifting device has a simple structure and occupies little space (L2≤1.5m), facilitating the lifting of the entire machine in confined spaces. The triangular lifting plate is preferably cut from 45GB / T699 steel plate, with three lifting holes drilled for the shackles. A 15t load test is conducted on the lifting plate. It features low material costs, easy processing, convenient transportation and use, and high safety and reliability. The center distance L1 of the diesel engine lifting eye bolts can be adjusted, offering strong adaptability. The preferred material is a D-type shackle with a threaded pin structure (GB / T25854) with holes and shoulders. The ultimate working load of D-type shackle 1 is preferably 10t (Grade 6), and the ultimate working load of D-type shackle 2 is preferably 20t (Grade 6). High-strength killed alloy steel is preferred, offering high strength, high reliability, and a high safety factor. It also provides strong compatibility with steel ropes, manual hoists, and the lifting plate. The preferred steel rope is a 10t double-twist steel wire rope, which is lightweight, high-strength, can withstand impact loads, has good flexibility, is easy to use, and is inexpensive. The manual hoist is preferably a 20t round structure made of alloy steel, with an 800Mpa high-strength lifting chain, medium-frequency quenching heat treatment, small in size, light in weight, easy to carry, low tensile force, and slow lifting. The two lifting points welded to the three decks are preferably made of Q235A carbon steel plates, which have strong weldability, cause less damage to the deck, and are easy to strengthen.

[0077] 3) The four-point support fixture for securing the diesel engine is preferably made of five independent Q235A carbon steel plates, cut, machined, and welded. It features pre-reserved weld bevels, full-fusion arc welding, high structural strength, and reliable welding. The uprights can be adjusted according to the lifting height L3 to accommodate diesel engine supports at different heights and create sufficient operating space for maintaining the main bearing cap. The bolt holes on the bottom plate match those on the I-beam, and the bolt holes on the top plate match those on the support bracket. The fasteners originally used for the rubber vibration isolators are used to securely connect the diesel engine to the bottom deck.

[0078] 4) For oil pan disassembly and cleaning protection devices, low-cost materials such as wood and plastic are selected and combined in design to meet the needs of protection, hoisting and other operations. It is highly practical, easy to manufacture and select. A single sheet of transparent plastic sheeting is preferred, laid on the oil pan. It is lightweight, easy to use, a disposable consumable, and can adapt to a large installation surface on the oil pan, preventing foreign objects and other contaminants from contaminating the oil pan lubrication system. Two sleepers, made of ordinary hardwood, are preferred, placed between the oil pan and the bottom deck to prevent contamination of the oil pan and facilitate hoisting. Hardwood planks, made of hard oak, are preferred, and the material must be able to withstand a 200kg load, free of cracks and other defects, for use during main bearing cap replacement operations inside the tank. Two-ton lifting slings, made of synthetic fiber, are preferred; they are soft and resilient, facilitating lifting and protecting the oil pan.

[0079] 5) A body opening and bolt tightening device used for disassembling and assembling main bearing caps. Used in combination, it allows for quick disassembly and assembly of main bearing caps. The bolt tightening pressure and body opening amount are stable and controllable, suitable for disassembly and assembly of various types of interference fit main bearing caps. The body opening device is ingeniously designed with matching left and right threads. The left side is designed with a left-hand thread connection, and the right side with a right-hand thread connection. Both studs have notches to increase the contact area with the body opening. The opening nut has a square head for tightening and a relief groove in the threaded hole. Using an open-end wrench to rotate the nut opens the body. The opening amount can be calculated based on the thread pitch, and the body opening should ideally be controlled within 0.5mm.

[0080] Example 2: A method for repairing the main bearing cover inside the tank of a high-power marine diesel engine, based on a modular tool for repairing the main bearing cover inside the tank, the method includes the following steps:

[0081] Step 1): Dismantling of peripheral systems: See Figure 1 , 4 As shown, disconnect the oil, water, gas, and electrical connections around the diesel engine 1, and remove all systems and devices in the engine compartment 3 that may affect the maintenance of the main bearing cover 1-3 of the diesel engine.

[0082] Step 2): Removal of the container: See [link / reference] Figure 1 , 4 As shown, remove the soundproof enclosure 2 around the diesel engine and disconnect the pipeline between the soundproof enclosure 2 and the diesel engine; this meets the requirements for lifting the diesel engine and repairing the main bearing cover.

[0083] Step 3): Preparations before lifting the diesel engine: See [link / reference] Figure 4 , 5 As shown, confirm the lifting point 11 of the whole machine on the third deck 3-3, install the triangular plate type whole machine lifting tool 4 and the manual hoist 10 on the lifting eye bolts 1-7 of the diesel engine, and adjust the height of the manual hoist to effectively connect with the lifting point 11 of the whole machine;

[0084] Step 4): Remove the vibration isolators and lift the diesel engine: See [link / reference] Figure 1 , 4 As shown in Figure 5, remove the rubber vibration isolators 1-9 between the support brackets 1-8 and the I-beams 1-10 at the bottom of the diesel engine 1, and use the manual hoist 10 to slowly and steadily lift the diesel engine 1 to the set height L3; install the support fixture 5 between the support brackets 1-8 and the I-beams 1-10 of the diesel engine, and support it at the engine supports of cylinders A4, A7, B4, and B7; place the lifting straps 12 and sleepers 7 under the oil pan 1-11.

[0085] Step 5): Remove the oil pan: See [link / reference] Figure 4 , 5 As shown in Figure 6, loosen the oil pan bolts 1-12, remove the connecting oil pipe from the oil pan 1-11 to the transmission box 1-14, and use slings 12 to slowly move the oil pan 1-11 out from between the hydraulic coupler 1-13 and the transmission box 1-14 at an angle α, and place it on the sleeper 7; cover the oil pan 1-11 with a clean plastic sheet 6, and lay plywood on the plastic sheet 6 for protection; lay a wooden board 8 under the main bearing cover that needs to be replaced to serve as a working platform;

[0086] Step 6): Remove the main bearing cover: See [link / reference] Figure 1 , 4 As shown, remove the main bearing caps 1-3KS at the output ends of both gears and 1-3KGS at the free end. Loosen the transverse tension bolts 1-6 and simultaneously use the machine body opening device 9 to open the machine body 1-1. Use a hydraulic tensioner to remove the main bearing cap nuts 1-5. Pressurize the hydraulic tensioner with the manual pump starting from the set pressure and check if the nuts can be loosened every 5MPa increment. Pay attention to the changes in control oil pressure and the length of the main bearing studs 1-4. Remove the main bearing caps and mark and protect them.

[0087] Step 7): Copy the new main bearing cover: Use a precise 3D scanning and mapping method to fit a 3D digital model of the faulty main bearing cover, generate manufacturing drawings, and process a new main bearing cover with controllable precision and quality.

[0088] Step 8): Install the new main bearing cap: See [link / reference] Figure 1 , 4As shown, use the engine body support device 9 to support the engine body 1-1, reinstall the corresponding new main bearing cover to the corresponding position of the diesel engine 1 according to the markings, and tighten the transverse tension bolts 1-6 and the main bearing cover nuts 1-5.

[0089] Step 9): Reinstall the oil pan: See Figure 1 , 2 As shown in 4, 5, and 6, remove the wooden board 8 and plastic sheet 6 from the oil pan 1-11. Use the pre-installed lifting strap 12 under the oil pan 1-11 to lift the oil pan 1-11 smoothly. Tilt the oil pan to avoid the hydraulic coupling 1-13. Install the oil pan into the machine body 1-1 and tighten the oil pan bolts 1-12.

[0090] Step 10): Reinstall the vibration isolator and mount the diesel engine: See [link / reference] Figure 1 , 3 As shown in 4 and 5, remove the sleeper 7 and sling 12 under the oil pan 1-11, remove the support fixture 5, reinstall the rubber vibration isolator 1-9, and use the manual hoist 10 to slowly lower the diesel engine so that the support bracket 1-8, rubber vibration isolator 1-9 and I-beam 1-10 are connected and then tightened.

[0091] Step 11): Box restoration: See Figure 1 As shown, restore the soundproof enclosure 2 around the diesel engine and connect the pipeline between the enclosure and the diesel engine;

[0092] Step 12): External system recovery: See Figure 1 As shown, restore the oil, water, gas, and electrical connections around the diesel engine, and reinstall all systems and devices in engine compartment 3 that affect the maintenance of the main bearing caps 1-3 of the diesel engine.

[0093] Preferably, the lifting height L3 of the diesel engine 1 is greater than or equal to 800 mm, and the lifting height L3 of the diesel engine 1 is less than the distance L2 from the diesel engine to the third deck.

[0094] Preferably, the height of the support fixture 5 is determined according to the lifting height L3 of the diesel engine 1.

[0095] The combined tool provided in this embodiment for in-cabin maintenance of the main bearing cover enables the use of a triangular lifting tool for hoisting the entire engine in confined spaces, a four-point support fixture for fixing the diesel engine, a device for disassembling and cleaning the oil pan, and a device for opening the hull and tightening bolts during the disassembly and assembly of the main bearing cover. This solves key technical challenges such as limited space for in-cabin maintenance of the main bearing cover, instability of the ship in water, low cleanliness, and high technical difficulty in assembling the main bearing cover. Based on the above devices, a completely new process for in-cabin maintenance of the main bearing cover is formed, which can effectively solve the technical difficulties of in-cabin maintenance of the main bearing cover of this type of diesel engine.

[0096] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0097] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A device for maintaining the main bearing cap inside a high-power marine diesel engine compartment, characterized in that: The equipment includes a combination tool for in-cabin maintenance of the main bearing cover, comprising a triangular plate-type engine hoist (4), a support fixture (5), an oil pan disassembly and cleaning protection device, and a fuselage opening device (9); the triangular plate-type engine hoist (4) is provided in two sets and is respectively installed on the output end and free end of the diesel engine (1), and the upper end of the triangular plate-type engine hoist (4) is connected to the three-tier deck (3-3) fixed in the engine room (3) via a manual hoist (10). The whole machine lifting point (11) is fastened and connected; the support fixture (5) is provided with four sets and is fixed at the bottom of the diesel engine (1) which is lifted a certain distance to support the diesel engine (1); the oil pan disassembly and cleaning protection device is used to disassemble the oil pan (1-11) and protect its cleanliness; the body opening device (9) is installed at the opening of the adjacent body (1-1) of the two main bearing covers (1-3) at the output end and free end of the diesel engine and is used to open the body (1-1).

2. The device for repairing the main bearing cover inside a high-power marine diesel engine compartment according to claim 1, characterized in that: The triangular plate type hoist (4) includes a triangular hoist plate (4-1). The two lower corners of the triangular hoist plate (4-1) are connected to a special steel rope (4-3) by a D-type shackle 1 (4-2). The lower end of the special steel rope (4-3) is used to connect and fasten to the lifting eye bolt (1-7) on the diesel engine (1). The upper corner of the triangular hoist plate (4-1) is connected to a manual hoist (10) by a D-type shackle 2 (4-4). The manual hoist (10) is fastened to the hoisting point (11) welded to the three-layer deck (3-3).

3. The device for repairing the main bearing cover inside a high-power marine diesel engine compartment according to claim 2, characterized in that: The distance between the two special steel ropes (4-3) at the bottom of the triangular lifting plate (4-1) is determined according to the lifting distance L1 of the lifting eye bolt (1-7) on the diesel engine.

4. The device for repairing the main bearing cover inside a high-power marine diesel engine compartment according to claim 1, characterized in that: The structure of the support fixture (5) includes two vertical plates (5-2) symmetrically fixed between the bottom plate (5-1) and the top plate (5-4), and a reinforcing plate (5-3) fixed between the two vertical plates (5-2); the bottom plate (5-1) is used to be fastened to the I-beam (1-10) on the diesel engine (1), and the top plate (5-4) is used to be fastened to the support bracket (1-8) on the diesel engine (1).

5. The device for repairing the main bearing cover inside a high-power marine diesel engine compartment according to claim 1, characterized in that: The oil pan disassembly and cleanliness protection device includes a plastic sheet (6) for laying on the oil pan (1-11), a sleeper (7) for padding under the oil pan (1-11), and a wooden board (8) for laying on the I-beam (1-10) at the output end and free end of the diesel engine (1) as a maintenance work platform.

6. The device for repairing the main bearing cover inside a high-power marine diesel engine compartment according to claim 1, characterized in that: The fuselage opening device (9) includes a left-hand stud (9-1) and a right-hand stud (9-3) for supporting the opening on the A and B sides of the fuselage (1-1), and an opening nut (9-2) for threaded connection between the left-hand stud (9-1) and the right-hand stud (9-3).

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