Low-speed marine diesel engine first order moment balance weight tooling

Abstract

The present application belongs to the technical field of counterweight tooling, and particularly relates to a first-order moment counterweight tooling for a low-speed marine diesel engine. The present application comprises a counterweight block main body, which is in a fan-shaped structure and has circular arc shapes on the upper and lower edges; a concave counterweight block main body mounting surface is arranged on one side surface of the counterweight block main body; a friction pad is arranged between the counterweight block main body mounting surface and the crankshaft end surface; the counterweight block main body is fastened by a first double-headed bolt and a first nut, and the same first balance double-headed bolt and first balance nut are arranged at symmetrical positions to balance the weight of the bolt itself; an additional counterweight block is detachably arranged on the counterweight block main body and fastened by a second double-headed bolt and a second nut, and is used for adjusting the first-order moment output value. The present application adopts a modular structure, the first-order moment is adjustable, is suitable for various MAN series main engines, improves the tooling utilization rate, reduces the inventory cost, and ensures the efficiency and accuracy requirements of the main engine performance test.

Description

Technical Field

[0001] This invention belongs to the field of balancing counterweight tooling technology, and relates to a first-order torque balancing counterweight tooling for low-speed marine diesel engines. Background Technology

[0002] Currently, with the rapid development of the global shipbuilding industry, orders for low-speed marine diesel engines continue to grow. As a core component of the marine power system, the performance and delivery cycle of low-speed diesel engines directly affect the overall ship construction schedule and shipowner satisfaction. In the design process of low-speed diesel engines, balancing the first-order torque is one of the key technologies for ensuring stable operation of the main engine, reducing vibration, and extending its service life. Traditionally, low-speed diesel engines typically employ an integrated balancing method to solve the first-order torque balance problem. This involves integrating balancing masses into the structural design of torsional vibration dampers or frequency-tuning impellers to achieve balance between the first-order reciprocating inertial force and centrifugal force. While this method can meet the balance requirements to a certain extent, its implementation is highly dependent on the timely supply of dampers and frequency-tuning impellers.

[0003] However, the global supply chain for marine low-speed diesel engine components is currently under significant pressure, especially for critical components such as torsional vibration dampers and frequency regulating wheels. Due to their complex manufacturing processes, long lead times, and concentrated supplier base, delivery delays are common. This results in engine manufacturers being unable to meet the first-order torque balance conditions during engine performance testing due to the lack of these components, thus affecting the testing process and engine delivery. Furthermore, different ship projects require different first-order torque balance values ​​due to variations in shafting configuration, power rating, and operating conditions. Designing dedicated balancing fixtures for each project not only increases design and manufacturing costs but also leads to a large variety of fixtures and difficulties in inventory management, further burdening companies.

[0004] Therefore, how to achieve effective balance of the first-order torque of the main engine and ensure the smooth conduct of performance tests when key components have not yet arrived has become a technical problem that low-speed diesel engine manufacturers urgently need to solve. Summary of the Invention

[0005] This invention addresses the problems of existing low-speed marine diesel engine first-order torque balancing fixtures, including low utilization rate, high inventory costs, low production efficiency, low balancing accuracy, unreliable test quality, complex structure, difficult installation, unsafe operation, and inability to meet the needs of various engine models. The invention proposes a first-order torque balancing counterweight fixture for low-speed marine diesel engines, comprising: a counterweight block body; the counterweight block body has a fan-shaped structure with arc-shaped upper and lower sides; one side of the counterweight block body has a recessed mounting surface; the mounting surface of the counterweight block body is used to connect with the crankshaft end face mounting surface via bolts; a friction pad is provided between the mounting surface of the counterweight block body and the crankshaft end face mounting surface to prevent relative sliding of the counterweight block body during high-speed rotation; the counterweight block body is secured by several first double-ended bolts and several first nuts. The connecting bolt holes on the crankshaft end face are fastened to the connecting mounting surface. On the crankshaft end face, the connecting bolt holes at positions symmetrical to the first double-ended bolt and the first nut are also provided with the same first balancing double-ended bolt and first balancing nut to balance the weight of the first double-ended bolt and the first nut. At least one additional counterweight can also be detachably provided on the counterweight block body. The additional counterweight is fastened to the preset mounting position of the counterweight block body by a number of second double-ended bolts and a number of second nuts to adjust the first-order torque output value of the tooling as a whole.

[0006] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the additional counterweight block has a fan-shaped structure with arc-shaped upper and lower sides.

[0007] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, a recessed additional counterweight mounting surface is provided on the opposite side of the main body of the counterweight block, for threaded connection with the additional counterweight block.

[0008] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the radius of the upper arc of the main body of the counterweight block is consistent with the radius of the inner ring of the crankshaft end face connection mounting surface.

[0009] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the number of first double-ended bolts is 3-6; the corresponding number of first nuts is 6-12.

[0010] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the screws of the first double-ended bolt and the second double-ended bolt are both stepped shafts.

[0011] According to the first-order torque balancing counterweight tooling for low-speed marine diesel engines described above, threaded holes are provided radially on the side walls of both the first nut and the second nut.

[0012] According to the first-order torque balancing counterweight tooling for low-speed marine diesel engines described above, the friction pad is made of a material with a high coefficient of friction.

[0013] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the depth of the recessed mounting surface of the counterweight block is 3-8mm.

[0014] According to the first-order torque balancing counterweight fixture for low-speed marine diesel engines described above, the weight of the main body of the counterweight is 1000kg-2000kg; the main body of the counterweight is used in combination with several additional counterweights, and the first-order torque range is 920kgm to 2700kgm.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. Improve tooling utilization and reduce inventory costs. This invention adopts a modular design, with the main counterweight and additional counterweights used in combination, covering a first-order torque range of 920 kgm to 2700 kgm, suitable for various MAN series low-speed diesel engines. Compared with the traditional method of designing dedicated tooling for each project, this tooling significantly reduces the number of dedicated tooling, lowers design and manufacturing costs, reduces inventory space and management costs, and improves the versatility and efficiency of tooling use.

[0017] 2. Ensures smooth performance testing of the main unit and shortens the delivery cycle. In the event that the torsional vibration damper or frequency-modulated wheel has not yet arrived, this invention can replace it to balance the first-order torque, meeting the conditions for main unit performance testing. The symmetrical arrangement of the friction pad and the first double-ended bolt ensures the stability and reliability of the tooling during high-speed rotation, avoiding the impact of unbalanced torque on test results, thereby guaranteeing timely delivery of the main unit and improving factory production efficiency.

[0018] 3. Improve balance accuracy and ensure test quality. The mounting surface of the counterweight body is a deep-machined surface, which fits tightly with the crankshaft end face, reducing installation errors; the friction pad is made of a high-friction coefficient material to prevent the fixture from slipping during rotation; the first double-ended bolts are symmetrically arranged to counteract the imbalance introduced by the weight of the bolts themselves. The above structural designs together ensure the balance accuracy of the fixture, improving the accuracy and reliability of the host machine performance test data.

[0019] 4. Simple structure, easy installation, and safe operation. The components of this invention are rationally designed, and the installation steps are clear, allowing operators to quickly disassemble and adjust the tooling. The additional counterweight is fixed to the main body via a second double-ended bolt and a second nut, facilitating easy assembly and disassembly. This allows for quick adjustment of the torque value according to different project requirements, reducing operational difficulty and labor intensity, and improving on-site safety.

[0020] 5. High adaptability, meeting the needs of various engine models. This invention allows for flexible adjustment of the first-order torque output value by changing the number and installation position of the additional counterweights, covering a torque range from 920 kgm to 2700 kgm, and is suitable for various MAN series low-speed marine diesel engines. Its compact structure requires little installation space, is not limited by engine model, and possesses excellent versatility and expandability, providing enterprises with an efficient and economical balancing solution. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the first-order torque balancing counterweight tooling for low-speed marine diesel engines according to the present invention.

[0022] Figure 2 This is a schematic diagram of the main body of the counterweight of the first-order torque balancing counterweight tooling for low-speed marine diesel engines of the present invention.

[0023] Figure 3 This is a schematic diagram of the first double-ended bolt and the first nut of the first-order torque balancing counterweight tooling for low-speed marine diesel engines of the present invention.

[0024] Figure 4 This is a schematic diagram of the additional counterweight block of the first-order torque balancing counterweight tooling for low-speed marine diesel engines of the present invention.

[0025] Figure 5 This is a schematic diagram of the second double-ended bolt and the second nut of the first-order torque balancing counterweight for low-speed marine diesel engines of the present invention.

[0026] Figure 6 This is a schematic diagram of the friction pad structure of the first-order torque balancing counterweight tooling for low-speed marine diesel engines of the present invention.

[0027] In the diagram: 1- Counterweight body; 11- Counterweight body mounting surface; 12- Crankshaft end face connection mounting surface; 13- Additional counterweight mounting surface; 2- Friction pad; 3- First double-ended bolt; 4- First nut;

[0028] 31-First balancing double-ended bolt; 41-First balancing nut; 5-Additional counterweight; 6-Second double-ended bolt; 7-Second nut; 30-Threaded hole. Detailed Implementation

[0029] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0030] like Figures 1 to 6As shown in this embodiment, the first-order torque balancing counterweight fixture for low-speed marine diesel engines is mainly used to replace key components such as torsional vibration dampers or frequency tuning wheels in order to balance the first-order torque of the main engine and ensure the smooth conduct of main engine performance tests. This fixture adopts a modular structure and can cover a first-order torque range of 920 kgm to 2700 kgm, making it suitable for various models of MAN series low-speed marine diesel engines.

[0031] The low-speed marine diesel engine first-order torque balancing counterweight fixture of this embodiment includes a counterweight body 1, a friction pad 2, a first double-ended bolt 3, a first nut 4, an additional counterweight 5, a second double-ended bolt 6, and a second nut 7. The counterweight body 1 has a fan-shaped structure with arc-shaped upper and lower sides. This shape can adapt to the installation space limitations of the crankshaft end face and optimize mass distribution while ensuring structural strength, resulting in a more reasonable center of gravity position. One side of the counterweight body 1 has a recessed counterweight body mounting surface 11, which is a precision-machined surface. The recess depth is preferably 3-8mm, and 5mm is used in this embodiment. The counterweight body mounting surface 11 is used to connect with the crankshaft end face mounting surface 12 via bolts. The precision-machined surface ensures a tight fit between the two, reducing installation gaps and improving balance accuracy.

[0032] A friction pad 2 is provided between the counterweight body 1 and the crankshaft end face mounting surface 12. The shape of the friction pad 2 matches the mounting surface 11 of the counterweight body, such as... Figure 6 As shown, it is made of a high-friction coefficient material, such as a specially treated rubber composite material or a metal-rubber composite gasket. When the tooling rotates at high speed with the crankshaft, it generates huge centrifugal and inertial forces. The friction pad 2 can significantly increase the static friction between the counterweight body 1 and the crankshaft end face, preventing relative sliding of the counterweight body 1 during high-speed rotation and ensuring a stable and reliable balance of the first-order torque. Without the friction pad 2, the bolt preload may not be sufficient to resist the tangential force during rotation, posing a risk of loosening during long-term operation or at high speeds.

[0033] The counterweight body 1 is fastened to the connecting bolt holes of the crankshaft end face mounting surface 12 by a number of first double-ended bolts 3 and a number of first nuts 4. The number of first double-ended bolts 3 can be selected according to the actual stress conditions, usually 3-6, and in this embodiment, 3 first double-ended bolts 3 are preferred. Correspondingly, each first double-ended bolt 3 needs to be equipped with two first nuts 4, so the number of first nuts 4 is 6-12, and in this embodiment, there are 6. One end of the first double-ended bolt 3 is screwed into the connecting bolt hole on the crankshaft end face, and the other end passes through the through hole on the counterweight body 1 and is fastened from the outside by the first nuts 4, thus firmly fixing the counterweight body 1 to the crankshaft end face.

[0034] On the crankshaft end face, at the connecting bolt holes symmetrically positioned to the first double-ended bolt 3 and the first nut 4, identical first balancing double-ended bolts 31 and first balancing nuts 4 are also provided. Without these symmetrical balancing bolts, the weight of the first double-ended bolt 3 and the first nut 4 would become an additional unbalanced mass, disrupting the tooling's balance. By installing identical first balancing double-ended bolts 31 and first balancing nuts 41 at symmetrical positions, the weight of the bolts and nuts is symmetrically distributed in the circumferential direction, canceling each other out and thus balancing the weight of the first double-ended bolt 3 and the first nut 4, preventing the introduction of additional unbalanced torque due to bolt arrangement.

[0035] like Figure 3 As shown, the screw of the first double-ended bolt 3 is preferably designed as a stepped shaft structure. The stepped shaft structure has better shear resistance, maintaining structural stability under large preload and alternating loads, preventing bolt breakage due to stress concentration. The first nut 4 has a radially arranged threaded hole 30 on its side wall, used to install a set screw or locking screw. When the first nut 4 is tightened to a predetermined torque, the set screw can be screwed into the threaded hole 30 to tighten the threaded surface of the first double-ended bolt 3, preventing loosening due to vibration; simultaneously, adding or removing set screws or locking screws can also balance the torque, improving the experimental accuracy of torque balance.

[0036] At least one additional counterweight 5 is detachably mounted on the main body 1 of the counterweight. On the side opposite to the mounting surface 11 of the main body 1, a recessed mounting surface 13 for the additional counterweight is provided. The mounting surface 13 is also a precision-machined surface, used for threaded connection with the additional counterweight 5. The additional counterweight 5 is fastened to a predetermined mounting position on the main body 1 by several second double-ended bolts 6 and several second nuts 7. The structure of the additional counterweight 5 matches the main body 1; it is a fan-shaped structure with rounded upper and lower sides, ensuring overall shape coordination and uniform force distribution.

[0037] The structure of the second double-ended bolt 6 and the second nut 7 is similar to that of the first double-ended bolt 3 and the first nut 4, also employing a stepped shaft design and an anti-loosening structure with radial threaded holes. One end of the second double-ended bolt 6 is screwed into the threaded hole on the counterweight body 1, and the other end passes through the through hole on the additional counterweight 5, and is tightened from the outside by the second nut 7, thus fixing the additional counterweight 5 to the counterweight body 1. This detachable connection method allows the additional counterweight 5 to be easily installed or removed as needed, enabling flexible adjustment of the tooling mass.

[0038] In this invention, the radius of the upper arc of the counterweight body 1 is consistent with the radius of the inner ring of the crankshaft end face connecting mounting surface 12. This structure ensures the geometric matching between the counterweight body 1 and the crankshaft end face, allowing the counterweight body 1 to be as close as possible to the crankshaft centerline, optimizing the center of gravity position, while avoiding interference with other crankshaft components.

[0039] The following explanation, using the torque calculation formula, illustrates how the tooling of this invention achieves first-order torque adjustment. The formula for calculating first-order torque is: M = r × F, where r is the radius of gyration from the tooling's center of gravity to the crankshaft center, and F is the total mass of the first-order torque balancing counterweight tooling. The counterweight body 1 itself has a fixed mass and center of gravity position. In this embodiment, the weight of the counterweight body 1 is preferably 1000kg-2000kg, and can be specifically designed according to the actual machine model, for example, 1397kg. When only the counterweight body 1 is installed, the tooling can provide a basic first-order torque of 920kgm, which can meet the basic test requirements of a single project.

[0040] When a larger first-order torque is required, an additional counterweight 5 can be installed on the main body 1 of the counterweight. The additional counterweight 5 can be a single piece or multiple pieces stacked together. After installing the additional counterweight 5, the total mass F of the tooling increases, and the center of gravity r may also change. By carefully designing the mass and installation position of the additional counterweight 5, the first-order torque of the tooling can be continuously adjusted within the range of 920 kgm to 2700 kgm, meeting the needs of different projects and machine models. In this embodiment, by configuring different numbers of additional counterweights 5, multiple torque output levels can be achieved, such as 1200 kgm, 1500 kgm, 1800 kgm, 2100 kgm, 2400 kgm, and 2700 kgm.

[0041] During installation, all bolts must be tightened strictly according to the specified torque value to ensure reliable connection. The recommended installation sequence is as follows: First, clean the crankshaft end face mounting surface 12 and the counterweight body mounting surface 11 to ensure they are free of oil and impurities; then place the friction pad 2 in the correct position; next, hoist the counterweight body 1 to align it with the crankshaft end face; then install the first double-ended bolt 3 and the first balance double-ended bolt 31, and initially tighten the first nut 4 and the first balance nut 41; then gradually increase the torque in multiple steps along the diagonal until the specified preload is reached; finally, screw the set screw into the threaded hole 30 for anti-loosening locking. When installing the additional counterweight 5, the additional counterweight mounting surface 13 also needs to be cleaned, and tightening should be performed following similar steps.

[0042] The structural design of the counterweight body 1 fully considers stress analysis and lightweight requirements. Its fan-shaped structure concentrates the material mainly at the outer edge away from the center of rotation, thereby obtaining a larger moment of inertia and balancing torque for the same mass. The arc structure on the top and bottom sides can avoid stress concentration at sharp corners and improve the fatigue life of the tooling.

[0043] The tooling of this invention can be easily disassembled and stored after use. Due to its modular structure, different models of MAN series low-speed marine diesel engines can share the same set of counterweight body 1. Only the additional counterweight 5 needs to be replaced or added as needed, which greatly reduces the number of special tooling, lowers inventory costs and management difficulty.

[0044] In practical applications, this tooling has been successfully applied to various models of MAN series low-speed marine diesel engines. For example, in the performance test of a certain model of engine, due to the failure of the torsional vibration damper to arrive on time, the tooling of this invention was used. By installing the main body 1 of the counterweight and an additional counterweight 5, the first-order torque reached 1500 kgm, which met the test requirements. The engine successfully completed the performance test and was delivered to the shipyard on time, avoiding the delay caused by waiting for parts.

[0045] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A first-order torque balancing counterweight fixture for low-speed marine diesel engines, characterized in that, include: The counterweight body (1) is a fan-shaped structure with arc-shaped upper and lower sides. A recessed counterweight body mounting surface (11) is provided on one side of the counterweight body (1). The counterweight body mounting surface (11) is used to be connected to the crankshaft end face mounting surface (12) by bolts. A friction pad (2) is provided between the counterweight body mounting surface (11) and the crankshaft end face mounting surface (12) to prevent relative sliding of the counterweight body (1) during high-speed rotation. The counterweight body (1) is fastened to the crankshaft end face mounting surface by several first double-headed bolts (3) and several first nuts (4). At the connecting bolt holes on the face (12), and at the connecting bolt holes on the crankshaft end face, which are symmetrical to the first double-ended bolt (3) and the first nut (4), there are also first balance double-ended bolts (31) and first balance nuts (41) that are the same as the first double-ended bolts (3) and the first nut (4); to balance the weight of the first double-ended bolts (3) and the first nut (4); at least one additional counterweight (5) can also be detachably provided on the counterweight body (1), and the additional counterweight (5) is fastened to the preset installation position of the counterweight body (1) by several second double-ended bolts (6) and several second nuts (7) to adjust the first-order torque output value of the tooling as a whole.

2. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The additional counterweight (5) has a fan-shaped structure with arc-shaped upper and lower sides.

3. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The counterweight body (1) has a recessed counterweight body mounting surface (11) on its side, and a recessed additional counterweight mounting surface (13) is provided on the opposite side of the side of the counterweight body mounting surface (11) for threaded connection with the additional counterweight (5).

4. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The radius of the upper arc of the counterweight body (1) is consistent with the radius of the inner ring of the crankshaft end face connecting mounting surface (12).

5. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The number of first double-ended bolts (3) is 3-6; the number of corresponding first nuts (4) is 6-12.

6. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The screws of both the first double-ended bolt (3) and the second double-ended bolt (6) are stepped shafts.

7. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, Both the first nut (4) and the second nut (7) have radially threaded holes (30) on their side walls.

8. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 1, characterized in that, The friction pad (2) is made of a material with a high coefficient of friction.

9. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 2, characterized in that, The depth of the recess in the mounting surface (11) of the counterweight block is 3-8mm.

10. The first-order torque balancing counterweight fixture for low-speed marine diesel engines according to claim 3, characterized in that, The weight of the main body of the counterweight (1) is 1000kg-2000kg; the main body of the counterweight (1) is used in combination with several additional counterweights (5), and the first-order torque range is 920kgm to 2700kgm.

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