Composite marine crankshaft with embedded multi-stage particle damping
By incorporating a multi-stage particle damping crankshaft with an inclined design and combining it with a nonlinear particle group, the problem of particle damping solidifying on the crankshaft due to centrifugal force is solved, achieving efficient vibration reduction and long service life under all working conditions, and adapting to the complex vibration characteristics of marine diesel engines.
Patent Information
- Application Number
- CN202512027616.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-02-10
AI Technical Summary
In the existing technology, when particle damping is applied to crankshafts, the particles solidify due to centrifugal force, making it impossible to maintain an effective fluidization state in a high centrifugal field, resulting in poor vibration reduction effect. In addition, traditional silicone oil vibration dampers are prone to aging and have high maintenance costs, making them difficult to adapt to the wideband multimodal vibration of marine diesel engines.
The design incorporates a composite marine crankshaft with embedded multi-stage particle damping. It employs an inclined damping cavity and a nonlinear damping particle group, combined with Coriolis force and air pumping effect, to ensure that the particles remain fluidized in a strong centrifugal field. Furthermore, it optimizes particle motion through multi-stage baffles and turbulence protrusions, thereby achieving a multi-frequency vibration reduction effect.
It achieves efficient vibration suppression under all operating conditions, broadens the vibration reduction frequency band, extends the damper life, reduces maintenance costs, and adapts to the complex operating conditions of marine diesel engines.
Smart Images
Figure CN121497776A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of marine propulsion technology, specifically to a composite marine crankshaft with embedded multi-stage particle damping. Background Technology
[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.
[0003] With the development of the shipbuilding industry, modern marine diesel engines are facing increasingly severe vibration control challenges. Traditional silicone oil vibration dampers are prone to aging, thermal failure, and high maintenance costs. More importantly, existing passive vibration damping technologies are difficult to adapt to the wide-bandwidth and multi-mode vibration characteristics of long-stroke engines.
[0004] Particle damping technology is considered an ideal alternative due to its excellent environmental resistance and wide frequency response. However, when attempting to apply particle damping to rotating components (such as crankshafts) in existing technologies, the "centrifugal dead zone" problem is commonly encountered: the powerful centrifugal force generated by high-speed rotation presses the particles against the wall, causing them to lose their energy dissipation capacity. Existing technologies lack a systematic structural solution, and simply adjusting the filling ratio or particle material is insufficient to maintain the effective fluidization state of the particles in a strong centrifugal field. Therefore, there is an urgent need for a crankshaft structure that can overcome the centrifugal dead zone and achieve efficient vibration reduction under all operating conditions. Summary of the Invention
[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a composite marine crankshaft with embedded multi-stage particle damping, which fundamentally overcomes the suppressive effect of rotational centrifugal force on particle damping and achieves efficient vibration suppression under all working conditions.
[0006] To achieve the above objectives, the present invention provides the following technical solution: A composite marine crankshaft with embedded multi-stage particle damping includes a main journal, a connecting rod journal, and a crank arm connecting the main journal and the connecting rod journal, wherein: The crank arm has at least one closed damping cavity inside the side near the counterweight. The damping cavity is filled with a group of nonlinear damping particles, and the longitudinal axis of the damping cavity is inclined relative to the radial plane of the crankshaft.
[0007] Furthermore, the nonlinear damping particle group includes a first dielectric particle and a second dielectric particle, wherein the first dielectric particle is a high-density particle and the second dielectric particle is a low-density particle with an elastic coating layer.
[0008] Furthermore, the nonlinear damping particle group occupies 40% to 60% of the damping cavity volume, and the volume ratio of the first medium particle to the second medium particle is 2:1 to 5:1.
[0009] Furthermore, the first medium particle is a tungsten carbide ball with a density of not less than 14.5 g / cm³, and the second medium particle is a PTFE-coated steel ball.
[0010] Furthermore, a partition is provided inside the damping cavity, which divides the damping cavity into multiple independent sub-chambers.
[0011] Furthermore, the partition plate is provided with through holes, the diameter of which is smaller than the particle size of the nonlinear damping particle group.
[0012] Furthermore, the volume ratio of the second medium particles in the multiple sub-chambers separated by the partition increases progressively from the inside to the outside in the radial direction of the crankshaft.
[0013] Furthermore, the inner wall surface of the damping cavity is provided with several circumferentially distributed turbulence protrusions.
[0014] Furthermore, the longitudinal axis of the damping cavity has an angle of 15° to 35° with respect to the radial plane of the crankshaft.
[0015] The technical solution provided by this invention has the following advantages compared with the prior art: 1. By designing the damping cavity to be tilted at a certain angle relative to the radial plane of the main journal, when the crankshaft undergoes torsional vibration (i.e., the angular velocity fluctuates), the tangential inertial force component is coupled with the Coriolis force, forcing the particles to slide and be ejected periodically along the inclined wall, thereby maintaining a "liquefied" state in a strong centrifugal field, avoiding particle solidification, and ensuring the vibration reduction effect. 2. A mixture of first and second medium particles is used. The first medium particles provide huge impact force with their ultra-high density. In low-frequency amplitude vibration, the vibration peak is rapidly attenuated through inelastic collision. The second medium particles are low-density elastic coated particles. Their low friction coefficient characteristics act as a lubricant between particles under high centrifugal pressure, preventing high-density particles from interlocking. The hysteretic deformation of the elastic layer provides viscoelastic damping, overcoming the shortcomings of collision damping under micro-amplitude vibration. 3. The damping cavity is divided into multiple sub-chambers by multiple sets of baffles to prevent all particles from accumulating to the bottom under the action of centrifugal force. At the same time, multiple sub-chambers are located at different positions in the radial direction of the crankshaft, forming multiple damping units with different natural frequencies, thus widening the vibration reduction frequency band. 4. Through holes are provided on the partition to allow airflow to pass through, and the vibration energy is further dissipated by the air pumping effect; 5. By setting up turbulence protrusions inside the damping cavity, when particles flow through, the turbulence protrusions forcefully change the trajectory of the particles, generating scattering and chaotic motion, transforming laminar flow into turbulent flow, and maximizing the increase of system entropy. 6. The multiple sub-chambers separated by the partition have a gradually increasing volume ratio of the second medium particles in the radial direction from the inside to the outside of the main journal. This ensures that the particle group can still maintain a certain "fluidity" and micro-sliding ability in the outermost chamber, avoiding the outer chamber from becoming an ineffective "dead weight". This maximizes the vibration reduction efficiency of the overall structure and prevents hard agglomeration caused by excessive local density, thus extending the service life and performance stability of the damper. 7. By coupling the inclined cavity with the Coriolis effect, the fluidization state of the particles can still be maintained in a high centrifugal force field, ensuring continuous and effective vibration reduction. Moreover, by utilizing the "dead weight" space in the crank arm counterweight area, the axial length of the engine is not increased. In addition to vibration reduction, it also has the function of balancing counterweight. This device integrates four mechanisms: inelastic collision (high frequency and large amplitude), surface friction (wide frequency), material viscoelasticity (low frequency and small amplitude), and aerodynamic damping (micro amplitude), adapting to the complex and ever-changing working conditions of marine engines. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.
[0017] Figure 1 The following is a schematic diagram of the structure of a composite marine crankshaft with embedded multi-stage particle damping in the embodiments below.
[0018] Figure 2 This is a top view of the crank unit structure in the following embodiments.
[0019] Figure 3 for Figure 2 Sectional view of AA.
[0020] Figure 4 for Figure 2 BB section view.
[0021] Figure 5 for Figure 3 A magnified view of a portion of point C in the middle.
[0022] The reference numerals in the attached diagram represent: 1-main journal, 2-crank arm, 3-connecting rod journal, 4-counterweight, 5-oil inlet, 6-lubricating oil passage, 7-oil outlet, 8-crank crank, 9-damping sleeve, 10-damping cavity, 11-first medium particle, 12-second medium particle, 13-partition, 14-sealing cover, 15-turbulence protrusion, 16-casting layer. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0024] like Figures 1-5 The invention relates to a composite marine crankshaft with embedded multi-stage particle damping, used in marine low-speed two-stroke diesel engines. It includes a main journal 1, a connecting rod journal 3, and a crank arm 2. The main journal 1, the two sets of crank arms 2, and the connecting rod journal 3 form a crank crank 8. The main journal 1 and the connecting rod journal 3 are respectively provided with an oil inlet 5 and an oil outlet 7, and a lubrication oil passage 6 is connected between the oil inlet 5 and the internal cavity of the connecting rod journal 3. A damping cavity 10 is provided inside the crank arm 2 near the counterweight 4, and a group of nonlinear damping particles is provided in the damping cavity 10.
[0025] Specifically, such as Figure 4 and Figure 5 As shown, in this embodiment, three sets of cylindrical through holes are provided on the outer edge of one side of the counterweight 4 of the crank arm 2. A set of damping sleeves 9 are fixed in each set of cylindrical through holes. The damping sleeves 9 are cylindrical shell structures with three sets of damping cavities 10 inside. The three sets of damping cavities 10 are distributed at intervals along the fan-shaped area of the counterweight 4, and the projection of the three sets of damping cavities 10 on the crankshaft rotation plane (cross section) occupies the main mass area of the counterweight 4. The axis of the damping cavity 10 is at a 20° angle to the radial direction of the main journal 1. The cavity is filled with first medium particles 11 and second medium particles 12, which together occupy 60% of the volume of the damping cavity 10. The first medium particles 11 are made of YG8 tungsten carbide spheres with a diameter d1=6mm and a density of 14.8g / cm³. 3The first medium, comprising 80% of the mixed particles, is primarily responsible for providing high-momentum impact. Utilizing its ultra-high density, it delivers enormous impact momentum. In low-frequency, high-amplitude vibrations, these particles act like countless miniature hammers, rapidly attenuating vibration peaks through inelastic collisions. The second medium, 12, is made of a 304 stainless steel core encased in a PTFE layer. With a core diameter of 3mm and a total diameter d2=4mm after encapsulation, it comprises 20% of the mixed particles. The PTFE layer, 0.5mm thick, provides lubrication and viscoelastic damping. The PTFE coating has an extremely low coefficient of friction, acting as a lubricant between particles under high centrifugal pressure to prevent high-density particles from interlocking. The hysteretic deformation of the elastic layer provides viscoelastic damping, overcoming the inadequacy of impact damping under micro-amplitude vibrations.
[0026] The damping cavity 10 has multiple sets of porous baffles 13 spaced along its length to divide it into multiple independent sub-chambers. This prevents all particles from being compressed at the bottom (i.e., the farthest end) of the cavity under centrifugal force, ensuring that there are active particle groups at different radii. The multiple sub-chambers also form multiple damping units with different natural frequencies, thus broadening the vibration reduction frequency band. The through holes on the baffles 13 allow airflow to pass through, further dissipating vibration energy by utilizing the air pumping effect.
[0027] Furthermore, the volume percentage of the second medium particles 12 in the multiple sub-chambers increases progressively from the inside out. In this embodiment, the proportion of the second medium particles increases to 45% in the outermost sub-chamber (where centrifugal force is greatest). When the crankshaft rotates, the centrifugal force is proportional to the radius of rotation. Therefore, the sub-chamber located on the outermost side of the crank arm (farthest from the center of rotation) experiences the greatest centrifugal pressure, and the particle group is most easily compacted to form a "solid embolism," resulting in immobility and energy consumption. By increasing the proportion of the second medium particles 12 in sub-chambers with larger radii, the concentration of "solid lubricant" in this high-pressure area is effectively increased. Utilizing the extremely low coefficient of friction (PTFE characteristics) and elasticity of the second medium particles, the equivalent internal friction angle of the particle group under high pressure is reduced, preventing high-density hard particles from becoming trapped. Under extreme centrifugal force, the particles (first medium) interlock and lock together, ensuring that even in the outermost chamber, the particle group can still maintain a certain "fluidity" and microscopic sliding ability. This allows each sub-chamber of the damping cavity 10 at different radii to be in optimal working condition, preventing the outer chamber from becoming ineffective "dead weight" and thus maximizing the overall vibration reduction efficiency of the structure. In addition, under strong centrifugal field, particles of different densities are prone to segregation, with heavy particles settling to the bottom and light particles floating to the top. Pre-filling the bottom (outer side) with a higher proportion of lightweight elastic particles can offset some of the tendency of excessive accumulation of heavy particles caused by centrifugal separation, maintain the uniformity of the mixed particle system, prevent hard agglomeration caused by excessive local density, and extend the service life and performance stability of the damper.
[0028] The inner wall of the damping cavity 10 is also provided with turbulence protrusions 15. When particles flow through, the turbulence protrusions 15 forcefully change the particle trajectory, generating scattering and chaotic motion, transforming laminar flow into turbulent flow, maximizing entropy increase, and thus increasing energy dissipation.
[0029] When the crankshaft rotates, the centrifugal force F C Radial outward, when torsional vibration occurs, the tangential inertial force F t Perpendicular to the radial direction, F t The continuous propulsion of the particles along the slope, coupled with the torsional vibration of the crankshaft (changes in angular acceleration) and gravity (periodic changes), provides reverse or tangential disturbances, keeping the particle group in a "shear rheological state" and completely eliminating static dead zones. In addition, the inclined design introduces the Coriolis effect, causing the particles to be subjected to lateral thrust while moving axially, resulting in spiral tumbling and significantly increasing the collision frequency between particles, thus maintaining the particles in a "liquefied" state in a strong centrifugal field.
[0030] In the actual manufacturing process of this device, the damping sleeve 9 is formed by split welding. Specifically, it consists of two sets of cylindrical shells with one end uncovered and one set of cylindrical shells with both ends uncovered. One set of cylindrical shells with one end uncovered is pre-processed with turbulence protrusions 15 and coated with heat insulation coating on both the inner and outer walls. Then, a set amount of first medium particles 11 and second medium particles 12 are filled into the shell without the end uncovered. Next, the partition plate 13 is welded at the port using high-energy laser deep melting welding to complete the processing of the first section (i.e., the innermost radial side) of the split sleeve. Then, the cylindrical shells with both ends uncovered are coaxially welded and fixed to the first section of the split sleeve. In the same way, an appropriate amount of damping particles are added and the partition plate 13 is welded. Finally, the other set of cylindrical shells with one end uncovered is welded and fixed to the second section of the split sleeve after an appropriate amount of damping particles are added, thus completing the manufacturing of the final damping sleeve 9.
[0031] The crankshaft 8 is pre-forged, and a blind hole, 6-10 mm larger than the outer diameter of the damping sleeve 9, is machined on its crank arm 2. Rough thread grooves are machined into the hole wall, and the hole is thoroughly cleaned of oil and iron filings using industrial solvents, then kept dry. Next, positioning and installation are performed. A PEEK positioning pad (thickness equal to the design gap) is attached to the outer wall of the damping sleeve 9. The damping sleeve 9 is inserted into the aforementioned blind hole, and external positioning fixtures are installed. The angle and depth of the damping sleeve 9 (i.e., the damping cavity 10) are adjusted to meet the designed tilt angle requirements. Then, a two-component steel powder-filled modified epoxy resin is selected as the casting material. The injection tube is extended to the bottom of the annular gap, and the resin is slowly injected using pump pressure, causing the resin level to rise from bottom to top (i.e., from the inside to the outside in the radial direction of the crankshaft), naturally expelling air. It should be noted that although epoxy resin... The curing exothermic peak is relatively low, but for large-volume casting, it is recommended to cast in two stages or control the curing agent ratio to ensure that the core temperature is always below 80°C, giving the PTFE particles an extremely generous safety margin. Curing at room temperature for 24 hours, followed by post-curing at 60-80°C, is used to increase the resin's crosslinking density and glass transition temperature, ensuring that it does not soften at engine operating temperatures, forming the casting layer 16. Finally, although epoxy resin has high strength, for redundancy considerations of ship safety regulations, a physical anti-reverse mechanism must be set up. A sealing cover plate 14 is installed at the blind hole opening, and the sealing cover plate 14 is welded to the surface of the crank arm 2 (care should be taken to avoid heat conduction to the casting layer 16) or bolted to prevent the damping sleeve 9 from flying out. Even if the casting layer 16 completely fails, the damping sleeve 9 is physically sealed inside the crankshaft.
[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.
Claims
1. A composite marine crankshaft with embedded multi-stage particle damping, comprising a main journal, a connecting rod journal, and a crank arm connecting the main journal and the connecting rod journal, characterized in that: The crank arm has at least one closed damping cavity inside the side near the counterweight. The damping cavity is filled with a group of nonlinear damping particles, and the longitudinal axis of the damping cavity is inclined relative to the radial plane of the crankshaft.
2. The composite marine crankshaft with embedded multi-stage particle damping according to claim 1, characterized in that, The nonlinear damping particle group includes a first medium particle and a second medium particle, wherein the first medium particle is a high-density particle and the second medium particle is a low-density particle with an elastic coating layer.
3. The composite marine crankshaft with embedded multi-stage particle damping according to claim 2, characterized in that, The nonlinear damping particle group accounts for 40% to 60% of the total volume of the damping cavity, and the volume ratio of the first medium particle to the second medium particle is 2:1 to 5:
1.
4. The composite marine crankshaft with embedded multi-stage particle damping according to claim 2, characterized in that, The first medium particle is a tungsten carbide sphere with a density of not less than 14.5 g / cm³. 3 The second medium particles are PTFE-coated steel balls.
5. The composite marine crankshaft with embedded multi-stage particle damping according to claim 3, characterized in that, The damping cavity is provided with a partition, which divides the damping cavity into multiple independent sub-chambers.
6. The composite marine crankshaft with embedded multi-stage particle damping according to claim 5, characterized in that, The partition plate is provided with through holes, the diameter of which is smaller than the particle size of the nonlinear damping particle group.
7. The composite marine crankshaft with embedded multi-stage particle damping according to claim 5, characterized in that, The volume percentage of the second medium particles in the multiple sub-chambers separated by the partition increases progressively from the inside to the outside in the radial direction of the crankshaft.
8. The composite marine crankshaft with embedded multi-stage particle damping according to claim 1, characterized in that, The inner wall of the damping cavity is provided with several circumferentially distributed turbulence protrusions.
9. The composite marine crankshaft with embedded multi-stage particle damping according to claim 1, characterized in that, The longitudinal axis of the damping cavity has an angle of 15° to 35° with respect to the radial plane of the crankshaft.