Fuel pump roller floating bush lubrication analysis method and system considering camshaft oil film time-varying support characteristics

Abstract

The invention provides a fuel pump roller floating bush lubrication analysis method and system considering camshaft oil film time-varying supporting characteristics in order to solve the problem that a coupling mechanism of camshaft bending vibration and floating bush lubrication characteristics in a marine diesel engine oil supply mechanism is not clear. Belongs to the technical field of high-pressure fuel pump camshafts. According to the method, a camshaft bearing transient lubrication model is constructed, and the camshaft bearing time-varying oil film rigidity and damping are solved to serve as a camshaft bending vibration boundary; time-varying stiffness and damping of a cam supporting oil film are obtained through solving by constructing a transient lubrication model of the floating bush and serve as the bending vibration boundary of the cam shaft; and taking the two groups of obtained oil film dynamic characteristic parameters as boundary conditions of cam shaft bending vibration analysis, obtaining a time-varying inclination angle of the roller, and calculating the transient lubrication characteristic of the floating bushing according to the time-varying inclination angle of the roller. The method is suitable for camshaft system design in a marine diesel engine oil supply mechanism, and the stability of equipment operation is effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of high-pressure fuel pump camshaft technology, specifically relating to the field of fuel pump roller floating bushing lubrication analysis technology that considers the time-varying support characteristics of camshaft oil film. Background Technology

[0002] With the continuous increase in the power and load of marine diesel engines, the requirements for the dynamics and tribological design of high-pressure fuel pumps are becoming increasingly stringent. The camshaft system is the core structure of the fuel pump, and the roller-floating bushing-roller pin (RFBP) structure is an important component of the camshaft system. Furthermore, the lubrication condition of key components determines the stability of equipment operation; therefore, conducting research on the lubrication characteristics of the RFBP structure is of great significance. During operation, the camshaft rotates, driving the rollers, which in turn drive the floating bushing. A lubricating oil film can be formed on the inner and outer sides of the floating bushing, and its load mainly comes from the plunger fuel pressure. Because the floating bushing has a certain rotational speed, compared with the roller-pin structure which only has a single layer of oil film, the roller-floating bushing-roller pin (RFBP) structure has the advantages of lower heat generation, smaller thermal deformation, and lower risk of seizure.

[0003] Currently, some research has been conducted on the lubrication characteristics of the roller-floating bushing-roller pin (RFBP) structure, but most of the findings focus on its steady-state characteristics. For example, some researchers have established a hydrodynamic lubrication model to conduct a preliminary analysis of the lubrication characteristics of the RFBP structure, optimized the inner and outer clearances of the floating bushing, and verified the validity of the conclusions through a 100-hour durability test. Others have established a steady-state lubrication model considering cavitation effects in Fluent software, and then used this model to optimize the oil hole design. Meanwhile, research on the steady-state lubrication performance of turbocharger floating ring bearings (FRBs), which also have a double-layer oil film structure, is relatively abundant. The research content mainly includes the lubrication characteristics of floating ring bearings with different structures and the refinement of lubrication models.

[0004] During actual fuel pump operation, the lubrication characteristics of the RFBP (Floating Bushing-Roller Pin) structure exhibit time-varying features due to changes in fuel pressure and cam surface velocity. While research on the transient characteristics of the RFBP structure has been conducted, results remain limited. Some researchers have used commercial software to analyze the transient lubrication state of the RFBP structure and optimized the fuel supply scheme. Others have considered the transient operating conditions of the cam mechanism, establishing a transient lubrication model for the RFBP structure and studying its transient lubrication state under different operating conditions and structural parameters. Furthermore, research indicates that camshaft vibration is significant during diesel engine operation and cannot be ignored in shaft vibration lubrication analysis; the camshaft oil film support characteristics show obvious time-varying behavior. Therefore, based on the transient lubrication model of the roller-floating bushing-roller pin (RFBP) structure, it is necessary to consider the influence of the time-varying support characteristics of the camshaft oil film, but relevant research in this field is still relatively scarce.

[0005] Furthermore, for floating ring bearings (FRBs), due to their long-term operation under high-speed, low-load conditions, phenomena such as oil film whirl and oil film instability are prone to occur. Some researchers use oil film force as a coupled transfer variable to reflect its nonlinear characteristics. Some have used the finite element method to analyze the multibody dynamics of the system, finding that the system will experience self-excited vibration within a specific speed range. Others have correlated the nonlinear vibration of the rotor with the turbulent lubrication model of the floating ring bearing through nonlinear oil film force, establishing a coupled model between the two. Still others have used Floquet theory to study the stability of the rotor-floating ring bearing system, improving the efficiency of system dynamics calculations.

[0006] However, unlike floating ring bearings (FRBs), whose rotor support characteristics do not change significantly due to relatively stable operating conditions, the roller-floating bushing-roller pin (RFBP) structure exhibits a significant difference. The RFBP structure shows obvious time-varying operating conditions, with its rotor support characteristics changing over time. The rotation of the rollers is driven by the external camshaft, while the operation of FRBs depends on the rotation of the internal rotor. The methods for considering vibration behavior in lubrication characteristic analysis also differ significantly between the two. Therefore, establishing a transient lubrication analysis model for the RFBP structure that considers the time-varying support characteristics of the camshaft oil film is of significant research value.

[0007] In summary, when analyzing the lubrication characteristics of the RFBP (Floating Roller Bushing-Roller Pin) structure, it is necessary to consider the influence of the time-varying characteristics of the camshaft oil film, but research in this area is still relatively weak. Although the coupling research between turbocharger rotor vibration and transient lubrication of floating ring bearings is quite extensive, the model assumptions of the RFBP structure and the floating ring bearing are also different due to the significant differences between them. Summary of the Invention

[0008] This invention addresses the problem of unclear coupling mechanism between camshaft bending vibration and floating bushing lubrication characteristics in marine diesel engine fuel supply mechanisms, which leads to a severe decline in engine reliability, efficiency, and lifespan. Therefore, it proposes a method and system for analyzing the lubrication of floating bushings of fuel pump rollers that considers the time-varying support characteristics of camshaft oil film.

[0009] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for lubrication analysis of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film, the method comprising the following steps: Step 1: Based on the working and structural parameters of the cam mechanism, solve for the time-varying load and rotational speed of the roller; Step 2: Based on the time-varying operating conditions of the camshaft bearing, construct a transient lubrication model of the camshaft bearing, and solve for the time-varying oil film stiffness and damping of the camshaft bearing, which serve as the boundary for camshaft bending vibration. Step 3: Based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and heat conduction of the floating bushing, construct a transient lubrication model of the floating bushing; and solve the model to obtain the time-varying stiffness and damping of the cam support oil film, which serves as the boundary for camshaft bending vibration. Step 4: Construct a camshaft vibration solution model based on the bending vibration of the camshaft, and solve the forced vibration of the camshaft system by determining the boundary of the oil film dynamic characteristics, and determine the time-varying tilt angle of the roller; Step 5: Calculate the transient lubrication characteristics of the floating bushing based on the time-varying tilt angle of the rollers calculated from the bending vibration of the camshaft.

[0010] Furthermore, the aforementioned operating parameters are variables that change during the operation of the cam mechanism; the structural parameters are fixed properties of the cam mechanism.

[0011] Furthermore, the time-varying load on the roller is calculated using a cam-roller dynamics model, with the following formula:

[0012] in, M For the mass driven by the camshaft, This is a function representing the plunger fuel pressure curve. For the plunger fuel force, For the inertial force of the roller assembly, The force is the plunger spring force. The pressure angle of the cam mechanism. The rotational speed of the cam and roller. , , These represent spring preload, spring stiffness, and cam lift, respectively.

[0013] Furthermore, the rotational speed of the roller is calculated using a cam-roller kinematic model, with the following formula:

[0014]

[0015]

[0016]

[0017] in, For the combined radius of curvature, For roller surface speed, lift Y The first and second derivatives correspond to the vertical velocity and acceleration of the roller, respectively.

[0018] Furthermore, the transient lubrication model for camshaft bearings is as follows:

[0019] in, h c This refers to the oil film thickness of the camshaft bearing. p c This refers to the oil film pressure of the camshaft bearing. and These are the density and viscosity of the lubricating oil, respectively. t For runtime, and For pressure-flow factor, Shear flow factor For contact flow factor, The combined roughness of the bearing bush and the camshaft. This refers to the circumferential angle of the camshaft bearing. The oil film pressure distribution is constrained by Reynolds boundary conditions, as described below:

[0020] The formula for calculating the oil film thickness of a camshaft bearing is:

[0021] in, c cFor the camshaft bearing oil film clearance, ε The eccentricity of the camshaft in the camshaft bearing; To account for the changes in oil film stiffness and damping during the transient process of the camshaft bearing, the following camshaft motion equation is introduced in the bearing:

[0022] in, m c For camshaft mass, x c and y c The camshaft is respectively in x and y Transient displacement in the direction, P c,x and P c,y The oil film of the camshaft bearing is respectively x and y reaction force in direction; To obtain the time-varying oil film stiffness and damping of the oil film inside the camshaft bearing, the small perturbation method is used for calculation.

[0023] Furthermore, based on the lubrication model of the floating bushing, the time-varying oil film stiffness / damping coefficient of the oil film inside the roller is calculated using the small perturbation method. , The oil film stiffness and damping value between the cam and the roller are obtained based on empirical values. The two together determine the cam support boundary conditions for calculating the camshaft bending vibration. The cam support boundary and the camshaft bearing support boundary together determine the camshaft bending vibration boundary conditions.

[0024] Furthermore, step 5 specifically includes: The time-varying tilt angle of the roller is calculated based on the camshaft bending vibration model. The transient lubrication characteristics of the floating bushing are calculated. The transient lubrication model of the floating bushing is based on the model in step 3, taking into account the tilt angle of the roller and the floating bushing. Time-varying tilt angle of floating bushing ( Based on the law of rotation, the calculation formula is as follows:

[0025] in, This is the radial rotational inertia of the floating bushing. It is positive when the inner and outer oil film pressures drive the floating bushing to rotate in the same direction, and negative when they rotate in opposite directions. Complete the calculation of the lubrication characteristics of the floating bushing considering the time-varying support characteristics of the camshaft oil film.

[0026] Secondly, the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of camshaft oil film described in this invention can be entirely implemented using computer software. Therefore, correspondingly, this invention also provides a fuel pump roller floating bushing lubrication analysis system considering the time-varying support characteristics of camshaft oil film.

[0027] Thirdly, the present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, performs the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film as described in any one of the preceding claims.

[0028] Fourthly, the present invention also provides a computer device, the device including a memory and a processor, wherein the memory stores a computer program, and when the processor runs the computer program stored in the memory, the processor executes the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of camshaft oil film as described in any one of the above-mentioned methods.

[0029] The beneficial effects of this invention are as follows: This invention provides a lubrication analysis method for a fuel pump roller floating bushing that considers the time-varying support characteristics of the camshaft oil film. The method obtains the time-varying stiffness and damping of the camshaft support oil film by solving for the time-varying oil film stiffness and damping of the camshaft bearing and by solving for the transient lubrication model of the floating bushing. These two sets of oil film dynamic characteristic parameters are used together as boundary conditions for camshaft bending vibration analysis to obtain the time-varying tilt angle of the roller. Based on the time-varying tilt angle of the roller, the transient lubrication characteristics of the floating bushing are calculated. This method features a well-developed model, good practicality, and can quantitatively evaluate the impact of camshaft bending vibration on the thickness, pressure, and temperature of the inner and outer oil films under harsh environmental conditions, achieving accurate prediction of the lubrication state under vibration.

[0030] Furthermore, this invention uses the instantaneous tilt angle of the roller as the transfer variable from vibration to lubrication, and calculates the instantaneous tilt angle of the floating bushing based on the fixed-axis rotation of a rigid body. This method can identify and improve vibration-sensitive parameters, enhance oil film load-bearing capacity, and becomes a potentially effective means for elastohydrodynamic lubrication analysis under complex vibration conditions of the roller-floating bushing-pin pair in the oil supply mechanism.

[0031] Furthermore, the coupled solution process of this invention achieves iterative convergence of vibration response and lubrication state, ensuring the accuracy and stability of the model under transient conditions.

[0032] This invention is applicable to the design of camshaft systems in marine diesel engine fuel supply mechanisms, effectively improving the stability of equipment operation. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a flowchart of the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of camshaft oil film, as described in an embodiment of the present invention. Figure 2 This is a schematic diagram of the cam mechanism in the diesel engine fuel pump mechanism described in an embodiment of the present invention; Figure 3 This is a schematic diagram of the dynamics and kinematics model of the cam-roller described in the embodiment of the present invention; Figure 4 This is a schematic diagram of the dynamic characteristic model described in an embodiment of the present invention; Figure 5 This is a camshaft bending vibration model in the fuel pump described in this embodiment of the invention, wherein... Figure 5 (a) is a schematic diagram of the camshaft in the fuel pump. Figure 5 (b) is a model of camshaft segment bending vibration; Figure 6 This is the floating bushing lubrication model described in the embodiments of the present invention, wherein, Figure 6 (a) is a schematic diagram of the transverse interface of the floating bushing structure. Figure 6 (b) is the heat conduction model of the floating bushing structure; Figure 7 This is a schematic diagram of the tilt angle of the cam, roller, and floating bushing described in an embodiment of the present invention. Detailed Implementation

[0035] The specific implementation details (such as experimental setup, operating procedures, data processing steps, and example parameters) of the "Lubrication Analysis Method for Fuel Pump Roller Floating Bushing Considering Time-Varying Support Characteristics of Camshaft Oil Film" provided in this specification are primarily intended for illustrative purposes rather than limiting definitions, aiming to help those skilled in the art thoroughly understand the principles and implementation of the invention. However, those skilled in the art should understand that these details represent only one feasible embodiment, and the core concept of the invention can be fully realized through other technical means or alternative solutions not described in detail, without departing from its spirit and essence. Furthermore, the omission of details of conventional experimental methods and apparatus known in the art in the specification is to avoid redundant information interfering with the understanding of the innovation points. This does not mean that these known technologies are not required during implementation, and those skilled in the art should be able to supplement and apply them based on their professional knowledge.

[0036] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0037] Example 1, Combination Figure 1 This embodiment addresses the problem that existing technologies lack the ability to reflect the bidirectional interaction between camshaft bending vibration and the transient lubrication characteristics of the RFBP structure. It provides a lubrication analysis method for the fuel pump roller floating bushing that considers the time-varying support characteristics of the camshaft oil film. The method includes the following steps: Step 1: Based on the working and structural parameters of the cam mechanism, solve for the time-varying load and rotational speed of the roller; Step 2: Based on the time-varying operating conditions of the camshaft bearing, construct a transient lubrication model of the camshaft bearing, and solve for the time-varying oil film stiffness and damping of the camshaft bearing, which serve as the boundary for camshaft bending vibration. Step 3: Based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and heat conduction of the floating bushing, construct a transient lubrication model of the floating bushing; and solve the model to obtain the time-varying stiffness and damping of the cam support oil film, which serves as the boundary for camshaft bending vibration. Step 4: Construct a camshaft vibration solution model based on the bending vibration of the camshaft, and solve the forced vibration of the camshaft system by determining the boundary of the oil film dynamic characteristics, and determine the time-varying tilt angle of the roller; Step 5: Calculate the transient lubrication characteristics of the floating bushing based on the time-varying tilt angle of the rollers calculated from the bending vibration of the camshaft.

[0038] The flowchart of the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film proposed in this embodiment is as follows: Figure 1As shown, firstly, the basic calculation parameters are initialized: based on the operating and structural parameters of the cam mechanism, the time-varying load and rotational speed of the roller are obtained through cam-roller dynamics and kinematic analysis. Then, a lubrication sub-model is established and solved to obtain the boundary conditions for camshaft bending vibration: based on the time-varying operating conditions of the camshaft bearing, its transient lubrication model is constructed, and the time-varying oil film stiffness and damping of the camshaft bearing are obtained; simultaneously, based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and thermal conduction effect of the floating bushing, a transient lubrication model of the floating bushing is constructed and solved to obtain the time-varying oil film stiffness and damping of the cam support oil film. These two sets of oil film dynamic characteristic parameters are used together as the boundary conditions for camshaft bending vibration analysis. Next, based on the determined oil film dynamic characteristic boundaries, the forced vibration of the camshaft system is solved to determine the time-varying tilt angle of the roller; finally, the lubrication characteristic analysis under coupled conditions is completed: based on the time-varying tilt angle of the roller calculated from the camshaft bending vibration, the transient lubrication characteristics of the floating bushing are calculated.

[0039] Example 2, Combination Figures 2 to 7 This embodiment is a detailed explanation of the lubrication analysis method for the floating bushing of the fuel pump roller that considers the time-varying support characteristics of the camshaft oil film, as described in Embodiment 1 above. Step 1: Based on the working and structural parameters of the cam mechanism, solve for the time-varying load and rotational speed of the roller; Specifically: The structural parameters of the cam mechanism are fixed properties of the cam mechanism, as shown in Table 1 (Structural Parameters of the Fuel Pump Camshaft): Table 1

[0040] The operating parameters of the cam mechanism are the variables that change during operation, as shown in Table 2 (Lubrication calculation parameters for roller-floating ring bushing-pin structure): Table 2

[0041] The dynamic and kinematic models of the cam-roller pair are calculated using single-mass kinematics and point-mass kinematics methods, respectively, to solve for the time-varying load and rotational speed of the roller.

[0042] like Figure 2 and Figure 3 The schematic diagram of the cam mechanism and the principle diagram of the cam-roller dynamics and kinematics model shown can be seen that when the cam rotates, it drives the roller, which in turn causes the floating bushing to rotate, while the roller pin is a fixed component. The force F acting on the roller is composed of three components: the piston fuel force... Inertial force of roller assembly and plunger spring force .definition For the overall mass of the plunger assembly. This is the total mass of the roller and driven component. For example... Figure 3 As shown, the pressure angle of the cam mechanism is denoted as... , and These are the cam rotation center and the base circle center, respectively. The geometric model defines the base circle radius as... The radius of curvature of the cam is The outer radius of the roller is The rotational speeds of the cam and the roller are denoted as follows: and .

[0043] Furthermore, the time-varying load on the roller is calculated using a cam-roller dynamics model, specifically: Under time-varying conditions, the dynamic load equation of the roller can be expressed as: (1) in, M For the mass driven by the camshaft, taking a high-pressure common rail fuel pump as an example. The function representing the plunger fuel pressure curve. For the plunger fuel force, For the inertial force of the roller assembly, The force is the plunger spring force. The pressure angle of the cam mechanism. The rotational speed of the cam and roller. , , These represent spring preload, spring stiffness, and cam lift, respectively.

[0044] pressure angle The formula is: (2) Furthermore, the rotational speed of the roller is calculated using a cam-roller kinematic model, specifically: like Figure 3 As shown, the geometric relationship of the cam mechanism follows the formula: (3) The calculation formula is as follows: (4) Lift Y The first and second derivatives correspond to the vertical velocity and acceleration of the roller, respectively. Therefore, the surface linear velocities of the cam and roller can be expressed as: (5) in, The radius of curvature is the composite radius. Roller surface velocity. u 2 is given by the following formula: (6) Roller speed ( The following equations are combined to determine the result: .

[0045] Step 2: Based on the time-varying operating conditions of the camshaft bearing, construct a transient lubrication model of the camshaft bearing, and solve for the time-varying oil film stiffness and damping of the camshaft bearing, which serve as the boundary for camshaft bending vibration. (7) in, h c This refers to the oil film thickness of the camshaft bearing. p c This refers to the oil film pressure of the camshaft bearing. and These are the density and viscosity of the lubricating oil, respectively. t For runtime, and For pressure-flow factor, Shear flow factor For contact flow factor, The combined roughness of the bearing bush and the camshaft. This refers to the circumferential angle of the camshaft bearing.

[0046] Furthermore, the oil film pressure distribution is constrained by Reynolds boundary conditions, as specifically stated below: (8) Furthermore, the formula for calculating the camshaft bearing oil film thickness is as follows: (9) in, c c For the camshaft bearing oil film clearance, ε This represents the eccentricity of the camshaft within the camshaft bearing.

[0047] Furthermore, to account for the changes in oil film stiffness and damping during the transient process of the camshaft bearing, the camshaft motion equation in the bearing is introduced: (10) in, m c For camshaft mass, x c and y c The camshaft is respectively in x and y Transient displacement in the direction,P c,x and P c,y The oil film of the camshaft bearing is respectively x and y reaction force in the direction.

[0048] Furthermore, in order to obtain the time-varying oil film stiffness and damping of the oil film inside the camshaft bearing, a small perturbation method is used for calculation (e.g., Figure 4 The diagram shows the dynamic characteristic model.

[0049] Figure 4 This is a schematic diagram of the dynamic characteristic model. x Direction is affected by -Δ x and +Δ x During interference, the center of the camshaft ( O c Move to position respectively O x1 and O x2 . θ 1 and θ 2 is the starting and ending angles of the oil film, which is the direction angle after the disturbance is generated. y Directional disturbance displacement -Δ y and +Δ y Afterwards, the camshaft center moves to O y1 and O y2 , θ 3 and θ 4 represents the initial and final angles of the oil film. (Using...) θ ′、 θ ′′ represents the oil film position angle before and after the disturbance.

[0050] The formula for calculating the time-varying oil film support stiffness of camshaft bearings is: (11) in, p x and p y These represent the oil film pressure after disturbance at a certain moment under transient conditions and... x and y The ratio, L c This refers to the width of the camshaft bearing.

[0051] The oil film damping coefficient of the camshaft bearing is determined using the velocity disturbance method, and the calculation formula is as follows: (12) Based on it K c,yy andC c,yy As one of the boundaries of camshaft bending vibration.

[0052] Step 3: Based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and heat conduction of the floating bushing, construct a transient lubrication model of the floating bushing; and solve the model to obtain the time-varying stiffness and damping of the cam support oil film, which serves as the boundary for camshaft bending vibration. Specifically: Since the support characteristic boundaries (time-varying stiffness, damping) of the camshaft bending vibration model are jointly determined by the camshaft bearing support boundary and the cam support boundary, and the cam support boundary is related to the oil film inside the roller, in order to calculate the time-varying stiffness and time-varying damping of the oil film inside the roller ( K r,yy , C r,yy The lubrication characteristics of the floating bushing should be calculated first. Figure 6 A transient model of the floating bushing is presented. Specifically, Figure 6 (a) shows a schematic diagram of the center plane of the structure. Initially, the center of the floating bushing is located at point... (Roller pin center), under load ( F Moved to under the action of ) Position; similarly, the center of the roller is determined by... Move to . Figure 6 (b) Presents the force and heat transfer models of the floating bushing. External load and reaction force of the outer layer of the oil film ( The combined action of the oil film and the reaction force of the outer layer of the oil film on the rollers are as follows: ) and inner reaction force ( The resultant force of the outer friction torque () acts on the floating bushing. ) drives the floating bushing to rotate, inner layer friction torque ( This would hinder its rotation. Furthermore, the floating bushing lubrication model employed a thermal balance analysis method.

[0053] The oil film pressure is calculated using the fluid incompressibility assumption, and the oil film pressure control equation is constructed (including the inner layer pressure). With outer pressure Unified representation as The unified form is: (13) in, and These represent the thickness of the oil film and the pressure, respectively. This indicates the viscosity of the lubricating oil. For the inner oil film: , , relative speed For the outer oil film: , , relative speed ; The viscosity of the lubricating oil takes into account the effect of temperature changes. The circumferential angle of the oil film. The relative rotational speed is given. Furthermore, the pressure distribution of the inner and outer oil films is determined by the combined effect of transient shear flow and extrusion flow.

[0054] Furthermore, oil film thickness Represented as: (14) in, and They are respectively x and y Displacement in direction, Indicates the axial position of the floating bushing. This represents the change in gap caused by thermal deformation.

[0055] Furthermore, the change in gap The calculation formula is: (15) in, The coefficient of thermal expansion is represented by , with the inner and outer thermal expansion coefficients denoted as respectively. and Under low-speed, high-load conditions, the effect of elastic deformation must be considered. This model takes into account the deformation of the floating bushing: due to the higher pressure of the inner oil film, elastic deformation will thicken the inner oil film, thereby causing the outer oil film to thin.

[0056] Furthermore, the deformation of the floating bushing The formula is: (16) in, For point The lubricating oil pressure at the location affects the inner and outer oil films. They are respectively represented as and .

[0057] Furthermore, the heat conduction balance expression for the inner and outer oil films is: (17) (18) in, and These represent the temperatures of the outer and inner oil films, respectively. and These correspond to the temperature changes of the outer and inner oil films, respectively. and It can be obtained by summing the oil inlet temperature and the oil film temperature rise. and These are the heat transfer coefficients of the inner and outer layers of the floating bushing, respectively, and are denoted uniformly as... Its expression is as follows: (19) Furthermore, the heat conduction equation for the floating bushing also needs to be taken into consideration, and its expression is as follows: (20) Wherein, the left side of the equation represents the heat conduction between the inner oil film and the floating bushing ( The right side represents the heat transfer between the outer oil film and the floating bushing. ).

[0058] Furthermore, to calculate the transient motion of the floating bushing under the action of oil film force, its radial / axial displacement can be calculated using the following formula: (twenty one) The formula for calculating the radial / axial displacement of the roller caused by oil film pressure is as follows: (twenty two) Floating bushing transient speed ( The calculation formula for ) is as follows: (twenty three) in, This represents the axial rotational inertia of the floating bushing.

[0059] Based on the lubrication model of the floating bushing, the time-varying oil film stiffness / damping coefficient inside the roller is calculated using the small disturbance method (the same method as the calculation method for the time-varying oil film stiffness and damping of the camshaft bearing). , The oil film stiffness and damping value between the cam and the roller are obtained based on empirical values. The two together determine the cam support boundary conditions for calculating the camshaft bending vibration. The cam support boundary and the camshaft bearing support boundary together determine the camshaft bending vibration boundary conditions.

[0060] Step 4: Construct a camshaft vibration solution model based on the bending vibration of the camshaft, and solve the forced vibration of the camshaft system by determining the boundary of the oil film dynamic characteristics, and determine the time-varying tilt angle of the roller; Specifically: The bending vibration of the fuel pump camshaft was calculated using the finite element method. Since the camshaft is a short and stubby structure, the Timoshenko beam-shaft model was selected. Figure 5A bending vibration model of a fuel camshaft is shown. For example... Figure 5 As shown in (a), the fuel pump camshaft includes a cam and a camshaft bearing. An oil film exists between the cam and the roller, as well as in the clearance of the camshaft bearing. The oil film can be considered equivalent to a spring and a damping element, and the cam can be considered equivalent to a concentrated mass point. Figure 5 (b) is a schematic diagram of the bending vibration model of a shaft segment element containing a cam, wherein... For cam mass, For oil film stiffness, For oil film damping, the vibration differential equation of the fuel pump cam is shown below: (twenty four) in, The mass matrix is ​​derived from the cam mass matrix ( ) and shaft segment mass matrix ( )composition; The damping matrix consists of the shaft end damping matrix and the oil film damping matrix; The inertia matrix is ​​derived from the cam inertia matrix ( ) and axis segment inertia matrix ( )composition; The stiffness matrix is ​​derived from the oil film stiffness matrix ( ) and shaft segment stiffness matrix ( )composition; The excitation matrix (the loads acting on each cam) ).

[0061] in, , and The expression is as follows: (25) Axis segment matrix ( , and The expression for ) is as follows: (26) Among them, coefficient It can be expressed by the following formula: (27) in, Let be the shear deformation coefficient of the shaft segment. The system damping matrix is ​​calculated using the Rayleigh damping model, and its expression is: (28) in, and The proportionality coefficient is determined by the system's first and second natural frequencies. Furthermore, the effect of oil film damping has been considered in the damping calculation. The Newmark-β method is used to numerically integrate the camshaft bending vibration control equation to determine the displacement difference between the front and rear ends of each cam, thereby determining the time-varying tilt angle of the rollers.

[0062] Step 5: Calculate the transient lubrication characteristics of the floating bushing based on the time-varying tilt angle of the rollers calculated from the bending vibration of the camshaft.

[0063] The transient lubrication characteristics of the floating bushing are calculated based on the time-varying tilt angle of the roller calculated using the camshaft bending vibration model. The transient lubrication model of the floating bushing incorporates the tilt angles of the roller and the floating bushing based on the model in step 3.

[0064] The formulas for calculating the inner and outer layer thicknesses of a floating bushing considering the tilt angle are as follows: (29) in, This is the transient tilt angle. The tilt angles of the floating bushing and the roller are denoted as follows: and .

[0065] Furthermore, Figure 7 To account for the tilt angles of the cam, roller, and floating bushing after bending vibration, the cam tilt angle determined by the displacement of the front and rear ends of the cam is considered as the roller tilt angle. Camshaft bending vibration does not affect the roller pin. When the oil film pressure center deviates from the center of the floating bushing, it causes radial rotation of the bushing, resulting in a time-varying tilt angle. ). and These represent the distances from the inner / outer oil film pressure positions acting on the floating bushing to the bushing center, respectively.

[0066] Time-varying tilt angle of floating bushing ( Based on the law of rotation, the calculation formula is as follows: (30) in, This is the radial rotational inertia of the floating bushing. It is positive when the inner and outer oil film pressures drive the floating bushing to rotate in the same direction, and negative when they rotate in opposite directions.

[0067] This completes the calculation of the lubrication characteristics of the floating bushing, taking into account the time-varying support characteristics of the camshaft oil film.

[0068] In summary, this invention establishes a coupled model of camshaft bending vibration and transient lubrication of floating bushings, proposes using the instantaneous tilt angle of the roller as the vibration-lubrication transmission variable, and introduces the vibration effect into the lubrication analysis through the roller tilt angle, achieving bidirectional mapping of multi-physics fields. Furthermore, the coupled solution process achieves iterative convergence of vibration response and lubrication state, ensuring the accuracy and stability of the model under transient conditions.

[0069] Example 3: The method for coupled analysis of bending vibration of a fuel pump camshaft and transient lubrication of a floating bushing described in any of the above embodiments can be entirely implemented using computer software. Therefore, correspondingly, this embodiment provides a system for coupled analysis of transient lubrication of a fuel pump camshaft and a floating bushing, the system comprising: A storage device for solving time-varying loads and rotational speeds of rollers based on the operating and structural parameters of cam mechanisms; This device is used to construct a transient lubrication model of a camshaft bearing based on time-varying operating conditions, solve for the time-varying oil film stiffness and damping of the camshaft bearing, and serve as a storage device for the bending vibration boundary of the camshaft. Based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and heat conduction of the floating bushing, a transient lubrication model of the floating bushing is constructed; and the model is solved to obtain the time-varying stiffness and damping of the cam support oil film, which serves as a storage device for the bending vibration boundary of the camshaft. A storage device for constructing a camshaft vibration solution model based on camshaft bending vibration, solving the forced vibration of the camshaft system by determining the boundary of oil film dynamic characteristics, and determining the time-varying tilt angle of the roller; A storage device for calculating the transient lubrication characteristics of floating bushings based on the time-varying tilt angle of the rollers calculated from the bending vibration of the camshaft.

[0070] Example 4: This example provides a computer-readable storage medium storing a computer program. When the computer program is run by a processor, it executes the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film described in any of the above examples.

[0071] Those skilled in the art will understand that implementing all or part of the processes in the above embodiments can be accomplished by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0072] Example 5: This example provides a computer device, which includes a memory and a processor. The memory stores a computer program. When the processor runs the computer program stored in the memory, the processor executes the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film as described in any of the above examples.

[0073] This embodiment provides a computer device. This part of the hardware device is a general model and is not shown in the figure. The system includes a processor and a memory. The processor and the memory can be connected by a bus or other means. The memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs and modules, as well as corresponding program instructions / modules. The processor executes various functional applications and data processing by running the non-transitory software programs, instructions and modules stored in the memory, so as to realize the lubrication analysis method and steps of the fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film in the above method embodiment.

[0074] The memory may include a program storage area and a data storage area, wherein the program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor, etc. Furthermore, the memory may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, mobile communication networks, and combinations thereof.

[0075] One or more modules are stored in the memory. When the processor executes, it performs the method steps in the embodiments. In this way, the invention objective can be achieved through the method, apparatus and process of the present invention. The specific details of the computer device described above can be understood by referring to the relevant descriptions and effects in the embodiments, and will not be repeated here.

[0076] The parameters required for this invention are defined in the above description, as shown in Figure 3.

[0077] Table 3

[0078] The above description of the technical solution provided by the present invention through several specific embodiments is intended to highlight the advantages and benefits of the technical solution provided by the present invention. However, the above-described specific embodiments are not intended to limit the present invention. Any reasonable modifications and improvements to the present invention, reasonable combinations of implementation methods and equivalent substitutions based on the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film, characterized in that, The method is as follows: Step 1: Based on the working and structural parameters of the cam mechanism, solve for the time-varying load and rotational speed of the roller; Step 2: Based on the time-varying operating conditions of the camshaft bearing, construct a transient lubrication model of the camshaft bearing, and solve for the time-varying oil film stiffness and damping of the camshaft bearing, which serve as the boundary for camshaft bending vibration. Step 3: Based on the time-varying load and rotational speed of the roller, combined with the elastic deformation and heat conduction of the floating bushing, construct a transient lubrication model of the floating bushing; and solve the model to obtain the time-varying stiffness and damping of the cam support oil film, which serves as the boundary for camshaft bending vibration. Step 4: Construct a camshaft vibration solution model based on the bending vibration of the camshaft, and solve the forced vibration of the camshaft system by determining the boundary of the oil film dynamic characteristics, and determine the time-varying tilt angle of the roller; Step 5: Calculate the transient lubrication characteristics of the floating bushing based on the time-varying tilt angle of the rollers calculated from the bending vibration of the camshaft.

2. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 1, characterized in that, Operating parameters are variables that change during the operation of the cam mechanism; structural parameters are fixed properties of the cam mechanism.

3. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 2, characterized in that, The time-varying load on the roller is calculated using a cam-roller dynamic model, with the following formula: in, M For the mass driven by the camshaft, This is a function representing the plunger fuel pressure curve. For the plunger fuel force, For the inertial force of the roller assembly, The force is the plunger spring force. The pressure angle of the cam mechanism. The rotational speed of the cam and roller. , , These represent spring preload, spring stiffness, and cam lift, respectively.

4. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 3, characterized in that, The rotational speed of the roller is calculated using a cam-roller kinematic model, with the following formula: in, For the combined radius of curvature, For roller surface speed, lift Y The first and second derivatives correspond to the vertical velocity and acceleration of the roller, respectively.

5. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 1, characterized in that, The transient lubrication model for camshaft bearings is as follows: in, h c This refers to the oil film thickness of the camshaft bearing. p c This refers to the oil film pressure of the camshaft bearing. and These are the density and viscosity of the lubricating oil, respectively. t For runtime, and For pressure-flow factor, Shear flow factor For contact flow factor, The combined roughness of the bearing bush and the camshaft. The circumferential angle of the camshaft bearing; the oil film pressure distribution is constrained by Reynolds boundary conditions, as detailed below: The formula for calculating the oil film thickness of a camshaft bearing is: in, c c For the camshaft bearing oil film clearance, ε Let be the eccentricity of the camshaft in the camshaft bearing; to account for the changes in oil film stiffness and damping during the transient process of the camshaft bearing, the camshaft motion equation in the bearing is introduced: in, m c For camshaft mass, x c and y c The camshaft is respectively in x and y Transient displacement in the direction, P c,x and P c,y The oil film of the camshaft bearing is respectively x and y The reaction force in the direction; in order to obtain the time-varying oil film stiffness and damping of the oil film inside the camshaft bearing, the small perturbation method is used for calculation.

6. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 1, characterized in that, Based on the lubrication model of the floating bushing, the time-varying oil film stiffness / damping coefficient of the oil film inside the roller is calculated using the small perturbation method. , The oil film stiffness and damping value between the cam and the roller are obtained based on empirical values. The two together determine the cam support boundary conditions for calculating the camshaft bending vibration. The cam support boundary and the camshaft bearing support boundary together determine the camshaft bending vibration boundary conditions.

7. The method for analyzing the lubrication of a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film according to claim 1, characterized in that, Step 5 specifically involves: The time-varying tilt angle of the roller is calculated based on the camshaft bending vibration model. The transient lubrication characteristics of the floating bushing are calculated. The transient lubrication model of the floating bushing is based on the model in step 3, taking into account the tilt angle of the roller and the floating bushing. Time-varying tilt angle of floating bushing Based on the law of rotation, the calculation formula is as follows: in, This is the radial rotational inertia of the floating bushing. It is positive when the inner and outer oil film pressures drive the floating bushing to rotate in the same direction, and negative when they rotate in opposite directions. Complete the calculation of the lubrication characteristics of the floating bushing considering the time-varying support characteristics of the camshaft oil film.

8. A lubrication analysis system for a fuel pump roller floating bushing considering the time-varying support characteristics of the camshaft oil film, characterized in that, The system is based on the fuel pump roller floating bushing lubrication analysis method that considers the time-varying support characteristics of the camshaft oil film, as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium contains a computer program that, when executed by a processor, performs the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film as described in any one of claims 1-7.

10. A computer device, characterized in that, The device includes a memory and a processor. The memory stores a computer program. When the processor runs the computer program stored in the memory, the processor executes the fuel pump roller floating bushing lubrication analysis method considering the time-varying support characteristics of the camshaft oil film as described in any one of claims 1-7.

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