A method for calculating dynamic wear of a plunger pair of a marine injection common rail pump

Abstract

This invention relates to a method for calculating the dynamic wear of a plunger pair in a marine common rail jet pump. First, a dynamic model is established to solve for the forces and micro-motions (eccentricity and tilt angle) of the plunger. Then, based on e and , the oil film thickness and pressure are calculated, and the oil film bearing capacity and lateral load are balanced through iteration. Next, surface roughness is introduced to determine the lubrication state, and the Reynolds equation is modified to characterize mixed lubrication. Force balance iteration is performed again to obtain a more accurate oil film pressure and thickness distribution. Finally, based on the results of the modified model, the wear amount is calculated using the micro-protrusion contact theory and the Arcard wear formula. This method, by coupling plunger micro-motion, oil film state, surface morphology, and operating parameters, realizes the calculation of dynamic wear, improves the operating condition adaptability of wear assessment, and provides a certain basis for the condition monitoring and life assessment of the plunger pair.

Description

Technical Field

[0001] This invention belongs to the technical field of internal combustion engine fuel systems, and relates to a method for calculating the dynamic wear of the plunger pair in a marine injection common rail pump, a method for calculating the wear of the plunger and sleeve in a marine injection common rail pump, and particularly a method for calculating the dynamic wear of the plunger pair based on oil film pressure iteration and micro-protrusion contact. Background Technology

[0002] The high-pressure common rail pump is a core unit of the marine engine fuel supply system, and its performance directly affects the engine's power output, fuel economy, and emissions. Within the high-pressure common rail pump, the plunger pair, consisting of the plunger and sleeve, is one of the most critical precision friction pairs. During operation, the plunger pair withstands extremely high cyclic pressures (typically exceeding 160 MPa) and undergoes high-speed reciprocating motion within micron-level clearances. Its tribological state and wear process directly determine the common rail pump's volumetric efficiency, pressure holding capacity, and service life.

[0003] With the increasing demand for clean energy in the global shipping industry, methanol, as a low-carbon fuel, is increasingly being used in marine engines. However, the introduction of methanol fuel has also brought new technical challenges to key engine components, especially the wear of precision parts in the fuel supply system. The physicochemical properties of methanol fuel differ significantly from traditional marine fuels. It is highly hydrophilic and readily miscible with lubricating oil, leading to emulsification. Emulsification significantly reduces the viscosity and film strength of the lubricating oil, drastically decreasing its lubrication performance. In self-lubricating plunger assemblies, the lack of continuous external lubrication supply makes lubrication conditions even more demanding. Methanol-induced lubricating oil emulsification further exacerbates boundary lubrication or dry friction, accelerating material wear.

[0004] In this context, research on plunger wear is particularly important. Increased wear in the micron-level clearance between the plunger and sleeve leads to increased fuel leakage, decreased injection pressure, and deteriorated atomization quality, resulting in reduced engine power, increased energy consumption, and excessive emissions. During long-term operation, plunger wear can also trigger sudden malfunctions, causing downtime for maintenance and resulting in significant economic losses. Therefore, accurately predicting and assessing plunger wear is crucial for condition monitoring, optimizing maintenance cycles, and improving system reliability and lifespan.

[0005] However, existing methods for calculating the wear of plunger pairs in marine high-pressure common rail pumps still have some limitations:

[0006] 1) Existing wear models are mostly based on steady-state assumptions and do not fully consider the micro-motion of the plunger during complex motion processes and its dynamic impact on the oil film state and contact load, resulting in deviations between wear predictions and actual conditions;

[0007] 2) Lack of systematic modeling of the influence of surface morphology. Most methods do not include the surface roughness of the plunger and sleeve in the wear calculation, and cannot accurately reflect the contribution of micro-protrusion contact to wear under mixed lubrication conditions;

[0008] 3) The wear calculation and multi-condition coupling capabilities are insufficient. Traditional studies often analyze the effect of a single factor on tribological properties, ignoring the coupling effect of micro-motion and surface morphology. Existing methods often fail to integrate the comprehensive influence of multiple factors such as cam speed, inlet pressure, and surface morphology on the wear process, making it difficult to achieve dynamic wear assessment under varying conditions.

[0009] Therefore, given the shortcomings of existing design methods, researchers in this field need to develop new calculation methods to overcome the aforementioned deficiencies in calculating the wear of the plunger pairs in marine jet common rail pumps. These methods should be able to more accurately describe the contact states of complex curved surfaces, helping to optimize the design and manufacturing processes, thereby improving the reliability, stability, and service life of the equipment. Summary of the Invention

[0010] In view of this, in order to solve the problem that existing wear models do not integrate the comprehensive influence of multiple factors such as micro-motion and surface morphology on the wear process, making it difficult to achieve dynamic wear assessment under varying working conditions, this invention provides a method for calculating the dynamic wear of the plunger pair of a marine jet common rail pump.

[0011] To achieve the above objectives, the present invention provides the following technical solution:

[0012] A method for calculating the dynamic wear of the plunger pair in a marine jet common rail pump includes the following steps:

[0013] S1. Establish a dynamic model for complex service conditions.

[0014] Input the initial motion conditions of the plunger pair, establish the dynamic model of the plunger pair, and calculate the magnitude of the forces and torques acting on the plunger during its motion.

[0015] S2. Iterative calculation of oil film pressure and oil film thickness based on eccentricity and tilt angle.

[0016] Input the initial eccentricity and initial tilt angle of the plunger relative to the plunger sleeve;

[0017] Based on the initial eccentricity and initial tilt angle, the initial oil film thickness distribution is calculated;

[0018] Based on the initial oil film thickness distribution, the corresponding oil film pressure distribution is calculated;

[0019] Determine whether the balance error between the oil film bearing capacity calculated from the oil film pressure distribution and the lateral load on the plunger meets the convergence requirements;

[0020] If not, then correct the eccentricity. and tilt angle Then, based on the corrected values, the step of calculating the oil film thickness distribution is performed again for iterative calculation;

[0021] If so, output the final oil film thickness distribution and oil film pressure distribution under the current iteration;

[0022] S3. Correction and Iteration of Hybrid Lubrication Model Incorporating Surface Roughness

[0023] Calculate the overall roughness of the contact surfaces between the plunger and the plunger sleeve;

[0024] Based on the aforementioned comprehensive roughness, the Reynolds model is modified to characterize the mixed lubrication state;

[0025] The oil film pressure distribution was recalculated using the modified Reynolds model.

[0026] Determine whether the balance error between the oil film bearing capacity and the lateral load after recalculation meets the convergence requirements;

[0027] If not, return to step S2 to correct the eccentricity. and tilt angle The steps are repeated, and the oil film thickness distribution is calculated again based on the corrected values, and the calculation is performed again iteratively.

[0028] If so, output the final oil film thickness distribution and oil film pressure distribution under the corrected model;

[0029] S4. Calculation of dynamic wear of plunger pair

[0030] Based on the final oil film pressure distribution and oil film thickness distribution output in step S3, the micro-protrusion contact pressure is calculated.

[0031] Using the Archard wear model, the wear of the plunger pair is calculated based on the contact pressure of the micro-protrusions and the relative sliding distance.

[0032] The beneficial effects of this invention are as follows:

[0033] 1. The method for calculating the dynamic wear of the plunger pair in a marine jet common rail pump disclosed in this invention solves for the eccentricity by establishing a dynamic model of the plunger pair. and tilt angle The dynamic equations for cam rotation angle (using the Runge-Kutta method) quantify the transient micro-motions of the plunger for the first time. Based on this, the micro-motion parameters are coupled into the iterative solution of oil film thickness and pressure, enabling the oil film state (load-bearing capacity) to respond in real-time to changes in motion and force. This closed-loop coupling of "dynamic model-oil film state" fundamentally changes the traditional approach of treating contact conditions as static, allowing wear calculations to simulate dynamic behavior in real working cycles, significantly improving the time-domain accuracy and realism of the predictions.

[0034] 2. The method for calculating the dynamic wear of the plunger pair in a marine jet common rail pump disclosed in this invention systematically incorporates surface morphology parameters and uses formulas... Calculate the overall roughness of the contact pair Furthermore, it innovatively uses film thickness ratio as a criterion for lubrication state. After determining mixed lubrication, it employs an average flow model, introducing pressure flow factor, shear flow factor, and contact flow factor to modify the Reynolds equation, thus including the influence of roughness on lubricant flow in the oil film pressure calculation. Based on the Greenwood-Tripp micro-protrusion contact theory, it calculates the actual contact pressure in the mixed lubrication zone, unifying macroscopic oil film lubrication with microscopic rough peak contact into a single model. This elevates the wear calculation mechanism from the "smooth surface assumption" to "real surface contact," more realistically reflecting the wear caused by the interaction of micro-protrusions under mixed lubrication.

[0035] 3. The dynamic wear calculation method for the plunger pair of a marine common rail injection pump disclosed in this invention comprehensively integrates structural parameters (plunger diameter, length, etc.), motion and operating condition parameters (cam speed, oil film inlet pressure), interface characteristics (surface roughness), and solved dynamic variables (eccentricity, tilt angle, oil film thickness). The method naturally incorporates the interaction of these factors through an iterative algorithm (for example, changes in cam speed alter slip velocity and power, thus affecting micro-motion and oil film state). Therefore, this method can directly simulate the wear process under different operating conditions (such as different speeds, different fuel pressures, and different surface finishes) by adjusting input parameters, achieving dynamic wear prediction under varying operating conditions. This provides a quantifiable and adjustable comprehensive theoretical model and calculation basis for shifting from "offline design evaluation" to "online condition monitoring and life prediction."

[0036] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0038] Figure 1 This is a flowchart illustrating the overall process for calculating the wear of key components in the marine jet common rail pump plunger according to the present invention.

[0039] Figure 2 This is a schematic diagram of the plunger pair structure and the cam-plunger motion relationship;

[0040] Figure 3 A simplified schematic diagram of the force analysis of the plunger dynamics model;

[0041] Figure 4 This is a schematic diagram of the micro-motion dynamics analysis of the plunger;

[0042] Figure 5 This is a schematic diagram of the mesh generation for finite difference computation.

[0043] Figure 6 This is a schematic diagram showing the contact between surface roughness and micro-protrusions.

[0044] Figure 7 This is a schematic diagram of the wear depth distribution of the plunger pair (axial and circumferential directions). Detailed Implementation

[0045] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0046] like Figure 1 The method for calculating the dynamic wear of the plunger pair in a marine common rail jet pump, as shown, includes the following steps:

[0047] S1. Establish a dynamic model for complex service conditions.

[0048] S11, such as Figure 2 The diagram illustrates the cam-plunger motion relationship, combined with the plunger diameter d and the cam base circle radius. cam maximum lift h, piston length L, cam radius Cam eccentricity Cam speed Based on structural parameters, a dynamic model of the plunger pair is established, and the plunger lift S, plunger axial velocity v, acceleration a, and cam pressure angle are solved. With the cam angle The changing pattern of is derived from the following calculation formula:

[0049] ;

[0050] ;

[0051] ;

[0052]

[0053] S12, such as Figure 3 The diagram clearly shows the complete force system of the plunger, including the force exerted by the high-pressure fuel in the plunger cavity. Spring force Axial inertial force Axial friction force Cam force and the combined force of oil film pressure wait.

[0054] The force exerted by the high-pressure oil in the plunger chamber on the plunger The calculation formula is:

[0055]

[0056] The spring force exerted by the plunger return auxiliary spring on the plunger. The calculation formula is:

[0057]

[0058] in, ρ is the preload spring force of the plunger; k is the spring stiffness coefficient; S is the plunger displacement;

[0059] Based on the forces acting on the plunger, the force balance and torque balance relationships of the plunger along the X and Y axes are as follows:

[0060]

[0061]

[0062]

[0063] in, The force exerted by the eccentric cam on the plunger. The axial friction force generated by the lateral force of the plunger. The axial inertial force of the plunger. , This is the reaction force of the plunger sleeve on the plunger;

[0064] When the plunger moves eccentrically or tilted, it drags the lubricating oil in the gap, forming a pressure distribution. The pressure at any point on the oil film... It is composed of both static pressure difference and dynamic pressure effect:

[0065]

[0066] By integrating the area of ​​this pressure distribution, the total supporting force of the oil film acting on both sides of the plunger can be obtained. , and the torque formed therefrom , ,and , The shearing action of the oil film generates a frictional torque that hinders motion.

[0067] S13. Based on the principle of lateral force balance and the relationship of moment balance, establish the lateral load balance equation for the plunger and the moment balance equation around the fulcrum, respectively:

[0068]

[0069] S14. By simultaneously solving the equations, the transient generalized Reynolds equation and the oil film thickness equation are constructed. Combining the relationship between oil film thickness and pressure, the actual plunger eccentricity e and tilt angle are derived. The dynamic equations are obtained, and the Runge-Kutta method is used to solve for their dynamic changes.

[0070] In constructing the transient generalized Reynolds equation, the following assumptions are made: a) the oil flow is laminar, and there is no turbulence or eddies in the entire flow field; b) there is no slippage of the gap oil on the mating surfaces of the plunger pair; c) the effects of inertial and volume forces of the gap oil are ignored; d) the oil film in the plunger pair is very thin, and pressure changes along the thickness direction of the oil film are not considered in the modeling; e) only the velocity gradients in the x and y directions are considered. Based on the above assumptions, the Navier-Stokes equations, which begin with the most fundamental fluid motion, are obtained:

[0071] ; ;

[0072] To address the complex rheological properties of lubricating oil, such as variable viscosity, a directional equivalent viscosity was introduced. The simplified momentum equation was integrated twice along the oil film thickness direction (z). Combined with the wall velocity boundary conditions, the general solution of the velocity distribution within the oil film was obtained.

[0073] Substituting this velocity expression into the formula for mass flow rate per unit width and integrating, we obtain:

[0074]

[0075] In the infinitesimal element direction and Substituting the mass flow rate in the direction into the above equation, we can obtain the continuity equation for the oil film in the piston pair clearance:

[0076]

[0077] In the above equation, the first two terms on the right side represent the dynamic pressure effect of the oil film in the plunger pair clearance, indicating the influence of the plunger pair clearance change on the lubricating oil film pressure; the third term on the right side represents the squeezing effect of the oil film in the plunger pair clearance, indicating the change in lubricating oil film pressure caused by the gradual approach of the plunger mating surfaces; the left side represents the squeezing effect caused by the radial micro-motion of the plunger, and the pressure field of the lubricating oil film in the plunger pair is the result of the combined action of the dynamic pressure effect and the squeezing effect.

[0078] like Figure 4 The Reynolds boundary condition is used to solve the Reynolds equation for the lubricating oil film in the plunger pair. The fuel pressure inside the plunger chamber is set as follows during the study. The pressure at the outlet is 0 MPa, therefore the boundary conditions of the lubricating oil film on the plunger pair are:

[0079] Piston pair pressure outlet boundary conditions:

[0080] Piston pair pressure inlet boundary conditions:

[0081] Periodic boundary conditions for the plunger pair: ,

[0082] Based on geometric relationships, the equation for the thickness of the lubricating oil film after it has expanded is as follows:

[0083] Where C is the average clearance between the plunger and the plunger sleeve; e is the plunger eccentricity. The angle between the line connecting the centers of any two cross sections in the axial direction of the plunger and the positive x-axis is defined, with a value range of [0, 2π].

[0084] S2. Iterative calculation of oil film pressure and oil film thickness based on eccentricity and tilt angle.

[0085] Input the initial eccentricity and initial tilt angle of the plunger relative to the plunger sleeve;

[0086] Based on the initial eccentricity and initial tilt angle, the initial oil film thickness distribution is calculated;

[0087] Based on the initial oil film thickness distribution, the corresponding oil film pressure distribution is calculated;

[0088] Determine whether the balance error between the oil film bearing capacity calculated from the oil film pressure distribution and the lateral load on the plunger meets the convergence requirements;

[0089] If not, then correct the eccentricity. and tilt angle The step of calculating the initial oil film thickness distribution is returned based on the corrected value, and iterative calculation is performed.

[0090] If so, output the final oil film thickness distribution and oil film pressure distribution under the current iteration;

[0091] The specific calculation methods for oil film thickness distribution and oil film pressure distribution are as follows:

[0092] S21. Based on the obtained plunger eccentricity... With tilt angle A dimensionless characterization model for oil film thickness was established to achieve dynamic quantification of oil film thickness by micro-motion. Combining the characteristics of fuel medium, a transient generalized Reynolds model incorporating micro-motion was established and dimensionless processing was completed to realize the coupling relationship between oil film pressure field and micro-motion state.

[0093] The dimensionless equation for oil film thickness is:

[0094] ,

[0095] in, Where C is the dimensionless eccentricity and C is the initial fit clearance. The angle is dimensionless, and L is the length of the plunger sealing section. Here, y is the dimensionless axial coordinate, and y is the actual axial coordinate. The angle between the line connecting the centers of the axial sections of the plunger and the X-axis.

[0096] The dimensionless transient generalized Reynolds equation is:

[0097] ,

[0098] in, The pressure is a dimensionless oil film pressure. Where is the plunger radius. Using dimensionless circular coordinates, For dimensionless time, For fuel dynamic viscosity, The speed of the piston's reciprocating motion.

[0099] S22, such as Figure 5 The dimensionless Reynolds model is meshed using the finite difference discretization method, and an over-relaxation iteration factor is set. The meshing is then repeated based on the input initial micro-motion parameters. Calculate oil film thickness distribution By substitution Solving the Reynolds equation yields the initial oil film pressure distribution. ,Will The process involves comparing the oil film bearing capacity obtained by integration with the lateral load of the plunger, and then adjusting the eccentricity or tilt angle through iterative steps until the oil film bearing capacity equals the lateral load. Finally, the oil film pressure distribution and minimum oil film thickness under different working conditions are obtained.

[0100] S3. Correction and Iteration of Hybrid Lubrication Model Incorporating Surface Roughness

[0101] Calculate the overall roughness of the contact surfaces between the plunger and the plunger sleeve;

[0102] Based on the aforementioned comprehensive roughness, the Reynolds model is modified to characterize the mixed lubrication state;

[0103] The oil film pressure distribution was recalculated using the modified Reynolds model.

[0104] Determine whether the balance error between the oil film bearing capacity and the lateral load after recalculation meets the convergence requirements;

[0105] If not, return to step S2 to correct the eccentricity. and tilt angle The steps are repeated, including calculating the initial oil film thickness distribution based on the corrected values, and then iterating again.

[0106] If so, output the final oil film thickness distribution and oil film pressure distribution under the corrected model;

[0107] The method for calculating the roughness of the contact interface between the plunger and the plunger sleeve is as follows:

[0108] like Figure 6 The figure shows a calculation formula based on the statistical principle of surface morphology, combined with the arithmetic mean deviation of the profiles of the plunger and plunger sleeve inner surfaces. The overall roughness of the contact pair was calculated. ,in The arithmetic mean deviation of the plunger surface profile. The arithmetic mean deviation of the inner surface profile of the plunger sleeve is given, with 1.111 as a conversion factor. The film thickness ratio is introduced. ( A lubrication condition determination model is established for the actual oil film thickness, and It is in a fully liquid lubrication state. It is in a mixed lubrication state.

[0109] Introducing a pressure-flow factor based on the average flow model:

[0110] The surface roughness texture of the plunger pair is isotropic, i.e. The pressure-flow factor is expressed as:

[0111]

[0112] Shear flow factor:

[0113] Take the morphology and texture of the mating surface The expression for the shear flow factor is:

[0114] ,

[0115] Contact flow factor:

[0116] Replace it with a fitting formula:

[0117]

[0118] The final modified Reynolds equation is:

[0119]

[0120] Establish a calculation model for oil film pressure and thickness under mixed lubrication, taking into account surface morphology;

[0121] S4. Calculation of dynamic wear of plunger pair

[0122] Based on the final oil film pressure distribution and oil film thickness distribution output in step S3, the micro-protrusion contact pressure is calculated.

[0123] Using the Archard wear model, the wear of the plunger pair is calculated based on the contact pressure of the micro-protrusion and the relative sliding distance.

[0124] Specifically, S41, the relative sliding speed of the interface contact plunger pair surface is directly related to the cam speed and plunger lift, and the single-cycle sliding distance of the plunger is... , This represents the maximum plunger lift. The plunger's reciprocating speed is determined by the cam drive characteristics, specifically the cam speed. Determine the cam angular velocity By combining the variation law of plunger lift with cam rotation angle, the instantaneous sliding speed under different working conditions can be derived.

[0125] S42. For mixed lubrication conditions, based on the Greenwood-Tripp micro-protrusion contact theory, and combining parameters such as the comprehensive elastic modulus of the contact pair, peak density, peak radius of curvature, roughness root mean square error, contact integral function, and the elastic modulus and Poisson's ratio of the plunger and plunger sleeve, the micro-protrusion contact pressure is constructed. Computational model:

[0126]

[0127] in, To measure the overall elastic modulus, , These are the elastic moduli of the plunger and the plunger sleeve, respectively. , These are the Poisson ratios of the two, For peak density, Let be the radius of curvature of the peak element. For the roughness standard deviation,

[0128] For contact integral functions.

[0129] The contact area of ​​the micro-protrusion is calculated using the nominal contact area and the integral function of the contact area:

[0130] ,

[0131] in, Nominal contact area The integral function is the contact area; thus, the contact load of the micro-convex body is obtained. .

[0132] S43. Based on the Archard wear model, establish the equation for calculating the wear of the plunger pair. ,in The wear coefficient is... To match the Vickers hardness of the auxiliary materials, The relative sliding distance. The wear volume is calculated by solving the equation. This yields the wear volume distribution along the axial and circumferential directions of the piston pair, incorporating the effects of cam speed and oil film inlet pressure on eccentricity and tilt angle, thus enabling dynamic calculation of wear under different operating conditions. For example... Figure 7 As shown, the three-dimensional surface plot visually illustrates the non-uniform distribution of wear volume in the axial and circumferential directions during the operation of the plunger assembly in a marine jet common rail pump. The three coordinate axes represent the circumferential position x (°), the axial position y (mm), and the wear depth (mm). The undulating surface reflects the varying wear levels at different working positions of the plunger pair. Its color gradient from blue to red corresponds to a gradual increase in wear volume, with the blue area showing less wear and better lubrication and contact conditions. The red area, with its significantly increased wear volume, represents the "hotspot" location with the highest risk of plunger pair failure. Locally raised high-wear zones (e.g., around axial y≈10mm and circumferential x≈2000°) clearly demonstrate the localized wear pattern. The formation of these high-wear areas is closely related to plunger micro-motion, micro-protrusion contact under mixed lubrication, and oil film pressure distribution, highlighting the coupled influence of cam speed, surface roughness, and fit clearance on plunger pair wear. Finally, the distribution results obtained using the coupled dynamics model, mixed lubrication correction, micro-protrusion contact theory, and the dynamic wear calculation method based on the Archard wear formula quantify the wear differences in the axial and circumferential directions of the plunger pair, providing a data-driven analytical basis for plunger pair surface profile optimization, processing technology improvement, and life assessment.

[0133] Finally, it should be noted that 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for calculating the dynamic wear of the plunger pair in a marine jet common rail pump, characterized in that, Includes the following steps: S1. Establish a dynamic model for complex service conditions. Input the initial motion conditions of the plunger pair, establish the dynamic model of the plunger pair, and calculate the magnitude of the forces and torques acting on the plunger during its motion. S2. Iterative calculation of oil film pressure and oil film thickness based on eccentricity and tilt angle. Input the initial eccentricity and initial tilt angle of the plunger relative to the plunger sleeve; Based on the initial eccentricity and initial tilt angle, the initial oil film thickness distribution is calculated; Based on the initial oil film thickness distribution, the corresponding oil film pressure distribution is calculated; Determine whether the balance error between the oil film bearing capacity calculated from the oil film pressure distribution and the lateral load on the plunger meets the convergence requirements; If not, then correct the eccentricity. and tilt angle Then, based on the corrected values, the step of calculating the oil film thickness distribution is performed again for iterative calculation; If so, output the final oil film thickness distribution and oil film pressure distribution under the current iteration; S3. Correction and Iteration of Hybrid Lubrication Model Incorporating Surface Roughness Calculate the overall roughness of the contact surfaces between the plunger and the plunger sleeve; Based on the aforementioned comprehensive roughness, the Reynolds model is modified to characterize the mixed lubrication state; The oil film pressure distribution was recalculated using the modified Reynolds model. Determine whether the balance error between the oil film bearing capacity and the lateral load after recalculation meets the convergence requirements; If not, return to step S2 to correct the eccentricity. and tilt angle The steps are repeated, and the oil film thickness distribution is calculated again based on the corrected values, and the calculation is performed again iteratively. If so, output the final oil film thickness distribution and oil film pressure distribution under the corrected model; S4. Calculation of dynamic wear of plunger pair Based on the final oil film pressure distribution and oil film thickness distribution output in step S3, the micro-protrusion contact pressure is calculated. Using the Archard wear model, the wear of the plunger pair is calculated based on the contact pressure of the micro-protrusions and the relative sliding distance.

2. The method for calculating the dynamic wear of a plunger pair as described in claim 1, characterized in that, Step S1 is based on the cam-plunger motion relationship, combined with the structural parameters of the plunger pair, including the plunger diameter d and the cam base circle radius. cam maximum lift h, piston length L, cam radius Cam eccentricity and cam speed A dynamic model of the plunger pair was established, and the plunger lift S, plunger axial velocity v, acceleration a, and cam pressure angle were solved. With the cam angle The changing pattern and corresponding calculation formula are as follows: ； ； ； ； The complete force system of the plunger includes the force of the high-pressure fuel in the plunger cavity. Spring force Axial inertial force Axial friction force Cam force and the combined force of oil film pressure ; The force exerted by the high-pressure oil in the plunger cavity on the plunger The calculation formula is: The spring force exerted by the plunger return auxiliary spring on the plunger. The calculation formula is: in, ρ is the preload spring force of the plunger; k is the spring stiffness coefficient; S is the plunger displacement; Based on the forces acting on the plunger, the force balance and torque balance relationships of the plunger along the X and Y axes are as follows: in, The force exerted by the eccentric cam on the plunger. The axial friction force generated by the lateral force of the plunger. The axial inertial force of the plunger. , This is the reaction force of the plunger sleeve on the plunger; When the plunger moves eccentrically or tilted, it drags the lubricating oil in the gap, forming a pressure distribution. The pressure at any point on the oil film... It is composed of both static pressure difference and dynamic pressure effect: By integrating the area of ​​this pressure distribution, the total supporting force of the oil film acting on both sides of the plunger can be obtained. , and the torque formed therefrom , ,and , The shearing action of the oil film generates a frictional torque that hinders motion.

3. The method for calculating the dynamic wear of the plunger pair as described in claim 2, characterized in that, Step S1: Based on the principle of lateral force balance and the relationship of moment balance, establish the lateral load balance equation for the plunger and the moment balance equation around the fulcrum, respectively: 。 4. The method for calculating the dynamic wear of a plunger pair as described in claim 3, characterized in that, In step S1, to construct the transient generalized Reynolds equation and the oil film thickness equation by simultaneously solving the equations, a directional equivalent viscosity is introduced to handle complex rheological properties such as variable viscosity that may exist in the lubricating oil. The simplified momentum equation is then integrated twice along the oil film thickness direction (z). Combined with the wall velocity boundary conditions, the general solution for the velocity distribution within the oil film is obtained. Substituting this velocity expression into the unit width mass flow rate formula and integrating, the continuity equation for the oil film in the plunger pair clearance is obtained. ； The Reynolds boundary condition was selected to solve the Reynolds equation for the lubricating oil film of the plunger pair; the fuel pressure inside the plunger cavity was set as follows during the study. The pressure at the outlet is 0 MPa, therefore the boundary conditions of the lubricating oil film on the plunger pair are: Piston pair pressure outlet boundary conditions: Piston pair pressure inlet boundary conditions: Periodic boundary conditions for the plunger pair: , Based on geometric relationships, the equation for the thickness of the lubricating oil film after it has expanded is as follows: Where C is the average clearance between the plunger and the plunger sleeve; e is the plunger eccentricity. The angle between the line connecting the centers of any two cross sections in the axial direction of the plunger and the positive x-axis is defined, with a value range of [0, 2π].

5. The method for calculating the dynamic wear of a plunger pair as described in claim 1, characterized in that, The specific calculation method for oil film thickness distribution and oil film pressure distribution in step S2 is as follows: Based on the actual eccentricity and tilt angle of the plunger obtained in step S1, a dimensionless characterization model of oil film thickness is established to realize the dynamic quantification of oil film thickness by micro-motion; combined with the characteristics of fuel medium, a transient generalized Reynolds model that takes into account micro-motion is established and dimensionless processing is completed to realize the coupling relationship between oil film pressure field and micro-motion state; The dimensionless Reynolds model is meshed using the finite difference discretization method, and an over-relaxation iteration factor is set; the meshing is then repeatedly applied based on the input initial micro-motion parameters. Calculate oil film thickness distribution By substitution Solving the Reynolds equation yields the initial oil film pressure distribution. ,Will The process involves comparing the oil film bearing capacity obtained by integration with the lateral load of the plunger, and then adjusting the eccentricity or tilt angle through iterative steps until the oil film bearing capacity equals the lateral load. Finally, the oil film pressure distribution and minimum oil film thickness under different working conditions are obtained.

6. The method for calculating the dynamic wear of a plunger pair as described in claim 5, characterized in that, The dimensionless equation for the oil film thickness in step S2 is: ， in, Where C is the dimensionless eccentricity and C is the initial fit clearance. The angle is dimensionless, and L is the length of the plunger sealing section. Here, y is the dimensionless axial coordinate, and y is the actual axial coordinate. Let be the angle between the line connecting the centers of the axial sections of the plunger and the X-axis; the dimensionless transient generalized Reynolds equation is: ， in, The pressure is a dimensionless oil film pressure. Where is the plunger radius. Using dimensionless circular coordinates, For dimensionless time, For fuel dynamic viscosity, The speed of the piston's reciprocating motion.

7. The method for calculating the dynamic wear of a plunger pair as described in claim 1, characterized in that, The method for calculating the surface roughness of the contact interface between the plunger and the plunger sleeve in step S3 is as follows: Based on the statistical principles of surface morphology, and combined with the arithmetic mean deviation of the profiles of the plunger and plunger sleeve inner surfaces, a calculation formula is used. The overall roughness of the contact pair was calculated. ,in The arithmetic mean deviation of the plunger surface profile. The arithmetic mean deviation of the inner surface profile of the plunger sleeve is given, with 1.111 as a conversion factor; the film thickness ratio is introduced. ( A lubrication condition determination model is established for the actual oil film thickness, and It is in a fully liquid lubrication state. It is in a mixed lubrication state; Based on the average flow model, pressure flow factor, shear flow factor, and contact flow factor are introduced to modify the Reynolds equation and establish a calculation model for oil film pressure and thickness under mixed lubrication that takes into account surface morphology.

8. The method for calculating the dynamic wear of a plunger pair as described in claim 7, characterized in that, In step S3: Introducing a pressure-flow factor based on the average flow model: The surface roughness texture of the plunger pair is isotropic, i.e. The pressure-flow factor is expressed as: Shear flow factor: Take the morphology and texture of the mating surface The expression for the shear flow factor is: 、 Contact flow factor: Replace it with a fitting formula: The final modified Reynolds equation is: Establish a calculation model for oil film pressure and thickness under mixed lubrication, taking into account surface morphology.

9. The method for calculating the dynamic wear of a plunger pair as described in claim 1, characterized in that, In step S4, the relative sliding speed of the interface contact plunger pair surface is directly related to the cam speed and plunger lift. The single-cycle sliding distance of the plunger is... , This represents the maximum lift of the plunger; The reciprocating speed of the plunger is determined by the cam drive characteristics, and the cam speed is... Determine the cam angular velocity By combining the variation law of plunger lift with cam rotation angle, the instantaneous sliding speed under different working conditions is derived; For mixed lubrication conditions, based on the Greenwood-Tripp micro-assurance contact theory, and combining the comprehensive elastic modulus of the contact pair, peak density, peak radius of curvature, roughness root mean square error, contact integral function, and the elastic modulus and Poisson's ratio of the plunger and plunger sleeve, the micro-assurance contact pressure is constructed. Computational model: in, To measure the overall elastic modulus, , These are the elastic moduli of the plunger and the plunger sleeve, respectively. , These are the Poisson ratios of the two, For peak density, Let be the radius of curvature of the peak element. For the roughness standard deviation, For contact integral functions; The contact area of ​​the micro-protrusion is calculated using the nominal contact area and the integral function of the contact area: ， in, Nominal contact area The contact load of the micro-convex body is obtained by integrating the contact area. ; Based on the Archard wear model, an equation for calculating the wear of the plunger pair is established. ,in The wear coefficient is... To match the Vickers hardness of the auxiliary materials, The relative sliding distance. The wear volume is calculated by solving the equation to obtain the wear volume distribution in the axial and circumferential directions of the piston pair. The influence of cam speed and oil film inlet pressure on eccentricity and tilt angle is incorporated to achieve dynamic calculation of wear under different working conditions.

10. The method for calculating the dynamic wear of a plunger pair as described in any one of claims 1 to 9 can accurately describe the contact state of complex curved surfaces and is applicable to the contact analysis of complex curved surfaces of any key component.

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