Engine connecting rod bearing temperature measurement point optimization method and system based on multi-physics field

Abstract

The present invention discloses an engine connecting rod bearing temperature measurement point optimization method and system based on multi-physical fields, which relates to the field of engine intelligent monitoring technology, including: obtaining the structural data of a marine engine, performing grid division, and performing dynamic substructure reduction, establishing a marine engine connecting rod bearing multi-body dynamics model, and obtaining the heat flow on the surface of the connecting rod bearing; establishing a connecting rod bearing temperature field simulation model, and obtaining a three-dimensional diagram of the temperature distribution of the bearing; establishing a connecting rod bearing stress field, and performing a simulation analysis of the stress field; combining the connecting rod bearing temperature field and the stress field, analyzing the circumferential temperature profile of the bearing surface and the stress on the connecting rod; combining the marine engine three-dimensional motion model, determining the optimal temperature monitoring point of the connecting rod bearing. The engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields provided by the present invention optimizes the marine engine connecting rod bearing temperature measurement points, and selects the optimal measurement points by simulating and analyzing the temperature field, stress field and installation feasibility.

Description

Technical Field

[0001] The present invention relates to the technical field of engine intelligent monitoring, and in particular to a method and system for optimizing temperature measurement points of engine connecting rod bearings based on multi-physical fields. Background Art

[0002] High efficiency, reliability, long life and intelligence are the development direction of modern marine engines. The connecting rod bearing is one of the main friction pairs of marine engines. It bears the gas force and alternating load generated by the combustion in the cylinder. Its working quality directly affects the reliability and service life of the crankshaft and connecting rod, and then affects the reliability and safety of the entire diesel engine and even the entire ship. In the development stage of marine engines, studying and improving the working performance of connecting rod bearings is one of the main contents of improving engine reliability; in the operation and maintenance stage of marine engines, monitoring the working performance of connecting rod bearings is one of the main contents of the engine's development towards long life and intelligence.

[0003] The temperature of the connecting rod bearing is one of the indicators for evaluating the performance of the connecting rod bearing. During the development stage of the marine engine, the technical parameters of the bearing, such as the material, clearance and thickness, will affect the performance of the bearing. By obtaining the temperature of the bearing, the lubrication effect and friction and wear state of the bearing can be indirectly reflected. During the operation and maintenance stage of the marine engine, the operating temperature of the bearing should be within the normal range and should not exceed the rated temperature limit to ensure the safety and reliability of the marine engine. In order to monitor and diagnose whether the connecting rod bearing has failed, it is necessary to obtain the temperature of the connecting rod bearing under different operating conditions of the marine engine as a judgment basis for its failure.

[0004] The temperature measurement method of the connecting rod bearing is to install a wireless passive temperature sensor at the connecting rod bearing by drilling to measure its temperature. However, the selection of the circumferential temperature measuring point of the connecting rod bearing is crucial. The crankcase space where the connecting rod bearing is located is limited, and the feasibility of its installation must be considered to avoid interference with other components during operation. At the same time, the position of the measuring point will also affect the strength of the connecting rod. Selecting a suitable measuring point can more effectively obtain the wear and lubrication conditions of the bearing. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention is proposed.

[0006] Therefore, the technical problem solved by the present invention is: in order to obtain the optimal monitoring point position of the connecting rod bearing temperature of a marine engine, an experimental method is generally adopted to install temperature sensors at different positions of the connecting rod on a connecting rod bearing test bench or an actual machine, and measure the temperature of the connecting rod bearing under different operating conditions of the engine in real time, and conduct comparative analysis; this method is subject to its time and cost costs, and the replacement of the bearing, installation of the temperature sensor, and experiments will consume a lot of time, and the cost of component processing also needs to be considered.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for optimizing the temperature measurement points of engine connecting rod bearings based on multi-physical fields, comprising:

[0008] Obtain the structural data of the connecting rod, bearing, and crankshaft of the marine engine, mesh the three-dimensional structure of the connecting rod, bearing, and crankshaft of the marine engine, and perform dynamic substructure reduction;

[0009] Based on Greenwood / Tripp contact and thermoelastic hydrodynamic lubrication theory, a multi-body dynamics model of the connecting rod bearing of a marine engine is established. The actual operating parameters of the marine engine are configured, and a multi-body dynamics simulation of the connecting rod assembly is performed to obtain the heat flow on the surface of the connecting rod bearing.

[0010] Establish a connecting rod bearing temperature field simulation model, use the heat flow and related boundary parameters on the connecting rod bearing surface as the input of the temperature field simulation model, simulate and analyze the connecting rod bearing temperature field, and obtain a three-dimensional diagram of the bearing temperature distribution;

[0011] Establish the connecting rod bearing stress field, apply the force acting on the connecting rod bearings at both ends, and conduct stress field simulation analysis; combine the connecting rod bearing temperature field and stress field to analyze the circumferential temperature profile of the bearing surface and the stress on the connecting rod;

[0012] Combined with the three-dimensional motion model of the marine engine, the feasibility of installing sensors at different measuring points is analyzed to determine the optimal temperature monitoring point of the connecting rod bearing.

[0013] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physics field described in the present invention, the dynamic substructure reduction is expressed as:

[0014] ,

[0015] ,

[0016] ,

[0017] { x m x s } = [ I − ( K ss − P j M ss ) − 1 K sm ] { x m } = T s x m ,

[0018] ,

[0019] in, , are the mass and stiffness matrices of the model respectively; , are displacement and force vectors, respectively; subscript , are the coordinates of the primary and secondary degrees of freedom, respectively; is the identity matrix; is the characteristic value; is the coordinate transformation matrix; for The transposed matrix of , , , are the mass model, stiffness matrix model and force vector model of the reduced model respectively. For the Order eigenvalue The value of .

[0020] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physics field described in the present invention, the Greenwood / Tripp contact is expressed as:

[0021] ,

[0022] { E * = 1 / [ ( 1 − v 1 2 ) / E 1 + ( 1 − v 2 2 ) / E 2 ] σ s = σ 1 2 + σ 2 2 ,

[0023] when , when lubrication is in the rough contact area,

[0024] ,

[0025] when , that is, when lubrication is in the full lubrication zone,

[0026] ,

[0027] in, , , , are the elastic modulus and Poisson’s ratio of the journal and bearing respectively; is the equivalent elastic modulus; is the radius of curvature of the micro-convex peak; is the micro-convex peak density; is the gap thickness; , are the roughness of the journal and bearing surface respectively; is the comprehensive surface roughness.

[0028] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields described in the present invention, the thermoelastic fluid dynamic lubrication theory is expressed as:

[0029] ρ · cp { ∂ T ∂ t + ( u − u j ) ∂ T ∂ x + w ∂ T ∂ z + 1 h [ v − y ( ∂ T ∂ t + ( u − u j ) ∂ T ∂ x + w ∂ T ∂ z ) ] ∂ T ∂ y } + T ρ ∂ ρ ∂ T | p ( ∂ p ∂ t + ( u − u j ) ∂ p ∂ x + w ∂ p ∂ z ) − κ h 2 ∂ 2 T ∂ y 2 =− η h 2 [ ( ∂ u ∂ y ) 2 + ( ∂ w ∂ y ) 2 ] + 1 h 3 p c μ 0 ( u j − u s ) ,

[0030] in, and are the fluid dynamic pressure and the gap height; , , for , , The velocity of the fluid in the direction; , and They represent the circumferential coordinate, radial coordinate and axial coordinate of the bearing development respectively; and are the peripheral speeds of the bearing and journal, respectively; is the density of the oil; is the specific heat of the oil; It’s time; is the oil temperature; are the circular coordinates; is the gap height coordinate; is the thermal conductivity of the oil; is the axial velocity of the oil film; is the concave-convex contact pressure; is the boundary friction coefficient.

[0031] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physics field described in the present invention, the simulation analysis includes calculating the load borne by the connecting rod bearing surface through a multi-body dynamics model, applying it to the connecting rod bearing stress field model, and obtaining the connecting rod bearing stress through stress field simulation;

[0032] For temperature field simulation, a single simulation is first performed. After multi-body dynamics simulation, the heat flux on the connecting rod bearing surface can be calculated. The temperature inside the crankcase of the marine engine is used as the boundary condition, and the heat flux on the connecting rod big end and small end bearing surfaces is used as the heat source. The temperature field simulation is carried out to obtain the connecting rod bearing temperature field and the bearing surface temperature profile.

[0033] Based on the Matlab Simulink simulation platform, the multi-body dynamics model and the temperature field model are combined, and multiple iterative simulations are performed. The surface temperature profile of the connecting rod bearing of the n-1th simulation is used as the input of the nth simulation until the connecting rod bearing temperature field enters a steady state and the simulation is stopped.

[0034] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields described in the present invention, wherein the feasibility of analyzing the installation of sensors at different measurement point positions includes establishing a three-dimensional motion model based on the connecting rod, bearing, and crankshaft geometric models of the marine engine;

[0035] In the three-dimensional motion model, the sensor geometry model is installed at different positions of the connecting rod, and the fixed antenna geometry model that receives the sensor signal is fixed;

[0036] By observing the three-dimensional movement process of the marine engine, it is determined whether the sensor interferes with the fixed antenna, crankcase, and oil pan position, and the feasibility of installing the connecting rod bearing temperature measurement point is determined.

[0037] As a preferred solution of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields described in the present invention, wherein, determining the optimal temperature monitoring point of the connecting rod bearing comprises simulating and obtaining the temperature field and stress field of the connecting rod bearing under different working conditions and different temperature measurement points of the marine engine;

[0038] From the perspective of reliability, analyze the stress field to determine whether there is stress concentration at different measuring points;

[0039] Analyze the temperature field and select the measuring points where the temperature change under different working conditions is greater than the preset threshold;

[0040] The interference of connecting rod bearing temperature measuring points installed at different positions is analyzed through the three-dimensional motion model of the marine engine, and the measuring points without interference are selected;

[0041] A comprehensive comparative analysis is carried out, and the measuring points where the stress change is less than the preset stress change threshold, the temperature change is greater than the preset temperature threshold and there is no interference are selected as the optimal temperature monitoring points for the connecting rod bearing.

[0042] Another object of the present invention is to provide an engine connecting rod bearing temperature measurement point optimization system based on multi-physical fields, which can improve the time efficiency and economic benefits of selecting connecting rod bearing temperature measurement points during the actual operation of marine engines by constructing an engine connecting rod bearing temperature measurement point optimization system based on multi-physical fields, and provide a technical basis for the design, production, monitoring and diagnosis of marine engine connecting rod bearings.

[0043] In order to solve the above technical problems, the present invention provides the following technical solutions: an engine connecting rod bearing temperature measurement point optimization system based on multi-physical fields, comprising: a preprocessing module, a marine engine connecting rod bearing multi-body dynamics module, a temperature field and stress field model establishment module, a marine engine connecting rod bearing simulation module, a marine engine connecting rod bearing temperature measurement point installation feasibility analysis module and a marine engine connecting rod bearing optimal temperature measurement point selection module; the preprocessing module is used to obtain the structural data of the connecting rod, bearing and crankshaft of the marine engine, mesh the three-dimensional structure of the connecting rod, bearing and crankshaft of the marine engine, and perform dynamic substructure reduction; the marine engine connecting rod bearing multi-body dynamics module is used to establish the marine engine connecting rod shaft based on Greenwood / Tripp contact and thermoelastic fluid dynamic lubrication theory. The multi-body dynamics model of the connecting rod bearing is configured with relevant parameters of the actual operation of the marine engine, and the multi-body dynamics simulation of the connecting rod assembly is performed to obtain the heat flow on the surface of the connecting rod bearing; the temperature field and stress field model establishment module is used to establish the temperature field and stress field simulation model of the connecting rod bearing; the marine engine connecting rod bearing simulation module is used to simulate and analyze the temperature field and stress field of the connecting rod bearing, and obtain a three-dimensional diagram of the temperature and stress distribution of the bearing; the feasibility analysis module for the installation of the temperature measuring point of the marine engine connecting rod bearing is used to combine the three-dimensional motion model of the marine engine to analyze the feasibility of installing the sensor at different measuring point positions; the marine engine connecting rod bearing optimal temperature measuring point selection module is used to combine the temperature field and stress field of the connecting rod bearing, analyze the circumferential temperature profile of the bearing surface and the stress of the connecting rod, and determine the optimal temperature monitoring point of the connecting rod bearing.

[0044] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields are implemented as described above.

[0045] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields as described above.

[0046] Beneficial effects of the present invention: The engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields provided by the present invention can simulate the temperature field and stress field of the connecting rod bearing of a marine engine under different working conditions, and analyze the temperature and stress borne by the connecting rod bearing;

[0047] The interference of connecting rod bearing temperature sensors installed at different positions can be checked through the three-dimensional motion model of the marine engine, and the feasibility of measuring point installation can be analyzed;

[0048] Based on the temperature field, stress field and measurement point installation feasibility analysis of the connecting rod bearing at different drilling positions, the optimal bearing temperature monitoring point can be selected without experimental methods, which improves the time and economic benefits of selecting the connecting rod bearing temperature measurement points during the actual operation of the marine engine, and provides a technical basis for the design, production, monitoring and diagnosis of the connecting rod bearing of the marine engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0050] Figure 1 An overall flow chart of a method for optimizing temperature measurement points of an engine connecting rod bearing based on multi-physics fields provided for one embodiment of the present invention.

[0051] Figure 2 A multi-body dynamics model of a connecting rod bearing in a method for optimizing temperature measurement points of an engine connecting rod bearing based on multi-physics fields is provided in one embodiment of the present invention.

[0052] Figure 3 A connecting rod bearing temperature field in a method for optimizing engine connecting rod bearing temperature measurement points based on multi-physical fields is provided in one embodiment of the present invention.

[0053] Figure 4 A connecting rod bearing stress field in a method for optimizing temperature measurement points of an engine connecting rod bearing based on multi-physical fields is provided in one embodiment of the present invention.

[0054] Figure 5 A flow chart of the simulation of the temperature field and stress field of a connecting rod bearing of a marine engine according to a method for optimizing the temperature measurement points of an engine connecting rod bearing based on multi-physical fields provided in one embodiment of the present invention.

[0055] Figure 6 An overall structural diagram of an engine connecting rod bearing temperature measurement point optimization system based on multi-physical fields provided for one embodiment of the present invention. DETAILED DESCRIPTION

[0056] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0057] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0058] Example 1, reference Figure 1-Figure 5 , which is an embodiment of the present invention, provides an engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields, comprising:

[0059] Preprocessing module, multi-body dynamics model of marine engine connecting rod bearing, temperature field and stress field model establishment module, marine engine connecting rod bearing simulation module, feasibility analysis module for installation of temperature measuring points of marine engine connecting rod bearing and optimal temperature measuring point selection module for marine engine connecting rod bearing.

[0060] The preprocessing module mainly includes:

[0061] Data acquisition is used to obtain the structural data and related technical parameters of the relevant parts of the marine engine, which involves the 3D models and material properties of the connecting rod, crankshaft, bearing, piston pin and other parts, as well as the cylinder pressure and lubricating oil temperature of the marine engine during actual operation;

[0062] Meshing mainly involves geometric cleaning, simplification and meshing of the 3D model to be modeled. At the same time, the connecting rod model is punched to simulate the sensor installation position, and related material properties such as stiffness, density, and Poisson's ratio are defined.

[0063] Dynamic substructure reduction is to divide the structure into simple substructures, and then reduce the original large degree of freedom system to a substructure model that retains the main degrees of freedom and includes mass, stiffness, and restoration matrix based on a specific algorithm. The motion equation is:

[0064]

[0065] in, , are the mass and stiffness matrices of the model respectively; , are displacement and force vectors, respectively; subscript , are the coordinates of the primary and secondary degrees of freedom, respectively.

[0066] From the second equation in formula (1), we can get:

[0067]

[0068] The solution is:

[0069]

[0070] is the eigenvalue, take its Order eigenvalue Value After calculation, formula (3) becomes:

[0071] { x m x s } = [ I − ( K ss − P j M ss ) − 1 K sm ] { x m } = T s x m

[0072] in, is the identity matrix; is the coordinate transformation matrix; for The transposed matrix of .

[0073] Substituting equation (4) into equation (1), the motion equation of the reduced model after transformation is:

[0074]

[0075] in, , , , which are the mass model, stiffness matrix model and force vector of the reduced model respectively.

[0076] The modules for establishing the multi-body dynamics model, temperature field and stress field model of the marine engine connecting rod bearing mainly include:

[0077] Based on Greenwood / Tripp contact theory and thermoelastic hydrodynamic lubrication, a multi-body dynamic model of connecting rod bearing of marine engine is established.

[0078] Using the Greenwood / Tripp contact theory, the contact pressure of the micro-convex peak on the bearing surface is:

[0079]

[0080] { E * = 1 / [ ( 1 − v 1 2 ) / E 1 + ( 1 − v 2 2 ) / E 2 ] σ s = σ 1 2 + σ 2 2

[0081] when , when lubrication is in the rough contact area

[0082]

[0083] when , that is, when lubrication is in the full lubrication zone

[0084]

[0085] in, , , , are the elastic modulus and Poisson’s ratio of the journal and bearing respectively; is the equivalent elastic modulus; is the radius of curvature of the micro-convex peak; is the micro-convex peak density; is the gap thickness; , are the roughness of the journal and bearing surface, is the comprehensive surface roughness.

[0086] For the thermoelastic hydrodynamic lubrication theory, the oil film energy equation in the non-stationary thermal balance is mainly considered, and the exact effect of different oil supply amounts on the bearing temperature distribution can be seen:

[0087] ρ · cp { ∂ T ∂ t + ( u − u j ) ∂ T ∂ x + w ∂ T ∂ z + 1 h [ v − y ( ∂ T ∂ t + ( u − u j ) ∂ T ∂ x + w ∂ T ∂ z ) ] ∂ T ∂ y } + T ρ ∂ ρ ∂ T | p ( ∂ p ∂ t + ( u − u j ) ∂ p ∂ x + w ∂ p ∂ z ) − κ h 2 ∂ 2 T ∂ y 2 =− η h 2 [ ( ∂ u ∂ y ) 2 + ( ∂ w ∂ y ) 2 ] + 1 h 3 p c μ 0 ( u j − u s )

[0088] in, and are the fluid dynamic pressure and the gap height; , , for , , The velocity of the fluid in the direction; , and They represent the circumferential coordinate, radial coordinate and axial coordinate of the bearing development respectively; and are the peripheral speeds of the bearing and journal, respectively; is the density of the oil; is the specific heat of the oil; It’s time; is the oil temperature; are the circular coordinates; is the gap height coordinate; is the thermal conductivity of the oil; is the axial velocity of the oil film; is the concave-convex contact pressure; is the boundary friction coefficient;

[0089] like Figure 2As shown in the figure, based on AVL Excite PU, a multi-body dynamic model of the connecting rod bearing of a marine engine is established based on dynamic substructure reduction. The parameters involved are shown in Table 1.

[0090] Table 1 Parameters required for multi-body dynamics modeling of connecting rod bearings for marine engines

[0091] ,

[0092] like Figure 3 As shown in the figure, based on the temperature field theory, a temperature field model of the connecting rod bearing of a marine engine is established.

[0093] The solution of the steady-state temperature field is based on Fourier's law, that is, the amount of heat passing through a certain cross section in unit time depends on the area of ​​the cross section and its temperature change rate, and is directly proportional. The direction of heat transfer is always from the high temperature area to the low temperature area, as shown in the following formula:

[0094]

[0095] in, is the heat flux density, in W / m2; is the cross-sectional area in m2; is thermal conductivity (also known as thermal conductivity coefficient), unit is W / (m·k); t is temperature, unit is k; is the coordinate, the unit is m; the negative sign indicates the opposite direction of temperature increase.

[0096] The temperature field model of the connecting rod bearing is established through Abaqus. The main input parameters involved include the ambient temperature of the connecting rod bearing and the heat transfer coefficient of the corresponding structure.

[0097] like Figure 4 As shown in the figure, based on the stress field theory, a stress field model of the connecting rod bearing of a marine engine is established.

[0098] The stress calculation formula is:

[0099]

[0100] in, is stress, is the magnitude of the external force, is the area under force.

[0101] The stress field model of the connecting rod bearing is established through Abaqus. The main parameters involved include the density, elastic modulus and Poisson's ratio of the connecting rod bearing material.

[0102] like Figure 5As shown, the marine engine connecting rod bearing simulation module mainly includes:

[0103] For stress field simulation, the load on the connecting rod bearing surface is first calculated through the multi-body dynamics model, and then applied to the connecting rod bearing stress field model, and the connecting rod bearing stress is obtained through stress field simulation.

[0104] For temperature field simulation, it takes multiple iterations to reach convergence. First, a single simulation is performed. After multi-body dynamics simulation, the heat flux on the connecting rod bearing surface can be calculated. The temperature inside the crankcase of the marine engine is used as the boundary condition, and the heat flux on the connecting rod big end and small end bearing surfaces are used as the heat source. The temperature field simulation is carried out to obtain the connecting rod bearing temperature field and the bearing surface temperature profile.

[0105] Based on the Matlab Simulink simulation platform, the multi-body dynamics model and the temperature field model are combined, and multiple iterative simulations are performed. The surface temperature profile of the connecting rod bearing of the n-1th simulation is used as the input of the nth simulation until the connecting rod bearing temperature field enters a steady state and the simulation is stopped.

[0106] The feasibility analysis module for the installation of temperature measurement points for connecting rod bearings of marine engines mainly includes:

[0107] Establish a three-dimensional motion model based on the geometric models of the connecting rod, bearing, crankshaft, etc. of the marine engine;

[0108] In the three-dimensional motion model, the sensor geometry model can be installed at different positions of the connecting rod, and the fixed antenna geometry model that receives the sensor signal can be fixed at the corresponding position;

[0109] By observing the three-dimensional movement process of the marine engine, it is possible to determine whether the sensor interferes with the fixed antenna, crankcase, oil pan and other positions, thereby determining the feasibility of installing the connecting rod bearing temperature measurement point.

[0110] The module for selecting the optimal temperature measurement point of the connecting rod bearing of a marine engine mainly includes:

[0111] The temperature field and stress field of the connecting rod bearing under different working conditions and different temperature measuring points of the marine engine are obtained by simulation. From the perspective of reliability, the stress field is first analyzed to observe whether there is stress concentration at different measuring points. At the same time, since the geometric model structure has changed due to drilling, it is also necessary to pay attention to whether there are stress changes in other parts of the connecting rod, and select measuring points with smaller stress changes. Secondly, the temperature field is analyzed, and measuring points with large temperature changes under different working conditions should be selected. Large temperature changes indicate that the convection heat transfer of the connecting rod bearing at this location and the friction heat transfer with the crank pin / piston pin are large. Thirdly, the interference of the connecting rod bearing temperature measuring points installed at different positions is analyzed through the three-dimensional motion model of the marine engine, and the measuring points without interference are selected. Finally, a comprehensive comparative analysis is performed, and the measuring points with stress changes less than the preset stress change threshold, temperature changes greater than the preset temperature threshold and no interference are selected as the optimal temperature monitoring points for the connecting rod bearing.

[0112] Example 2, reference Figure 6 , which is an embodiment of the present invention, provides an engine connecting rod bearing temperature measurement point optimization system based on multi-physics fields, including:

[0113] Preprocessing module, multi-body dynamics module for connecting rod bearings of marine engines, temperature field and stress field model building module, simulation module for connecting rod bearings of marine engines, feasibility analysis module for installation of temperature measuring points for connecting rod bearings of marine engines, and module for selecting the best temperature measuring points for connecting rod bearings of marine engines;

[0114] The preprocessing module is used to obtain the structural data of the connecting rod, bearing, and crankshaft of the marine engine, mesh the three-dimensional structure of the connecting rod, bearing, and crankshaft of the marine engine, and perform dynamic substructure reduction;

[0115] The marine engine connecting rod bearing multi-body dynamics module is used to establish a marine engine connecting rod bearing multi-body dynamics model based on Greenwood / Tripp contact and thermoelastic hydrodynamic lubrication theory, configure relevant parameters of the actual operation of the marine engine, perform multi-body dynamics simulation of the connecting rod assembly, and obtain the heat flow on the connecting rod bearing surface;

[0116] The temperature field and stress field model establishment module is used to establish a temperature field and stress field simulation model for a connecting rod bearing, and the heat flow and related boundary parameters on the surface of the connecting rod bearing are used as inputs of the temperature field simulation model to perform temperature field simulation; the load borne on the surface of the connecting rod bearing is used as inputs of the stress field simulation model to perform stress field simulation;

[0117] The marine engine connecting rod bearing simulation module is used to simulate and analyze the temperature field and stress field of the connecting rod bearing and obtain the three-dimensional diagram of the temperature and stress distribution of the bearing;

[0118] The feasibility analysis module for the installation of temperature measurement points of connecting rod bearings of marine engines is used to analyze the feasibility of installing sensors at different measurement points in combination with the three-dimensional motion model of marine engines.

[0119] The module for selecting the optimal temperature measurement point of the connecting rod bearing of a marine engine is used to combine the temperature field, stress field and three-dimensional motion model of the connecting rod bearing, analyze the circumferential temperature profile of the bearing surface and the stress of the connecting rod, judge whether there is interference, and determine the optimal temperature monitoring point of the connecting rod bearing.

[0120] Embodiment 3, an embodiment of the present invention, is different from the first two embodiments in that:

[0121] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0122] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0123] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0124] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0125] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An optimization method for measuring temperature points of engine connecting rod bearings based on multi-physics fields, characterized in that: include: Obtain the structural data of the connecting rod, bearing, and crankshaft of the marine engine, mesh the three-dimensional structure of the connecting rod, bearing, and crankshaft of the marine engine, and perform dynamic substructure reduction; Based on Greenwood / Tripp contact and thermoelastic hydrodynamic lubrication theory, a multi-body dynamics model of the connecting rod bearing of a marine engine is established. The actual operating parameters of the marine engine are configured, and a multi-body dynamics simulation of the connecting rod assembly is performed to obtain the heat flow on the surface of the connecting rod bearing. Establish a connecting rod bearing temperature field simulation model, use the heat flow and related boundary parameters on the connecting rod bearing surface as the input of the temperature field simulation model, simulate and analyze the connecting rod bearing temperature field, and obtain a three-dimensional diagram of the bearing temperature distribution; Establish the connecting rod bearing stress field, apply the force acting on the connecting rod bearings at both ends, and conduct simulation analysis; combine the connecting rod bearing temperature field and stress field to analyze the circumferential temperature profile of the bearing surface and the stress on the connecting rod; Combined with the three-dimensional motion model of the marine engine, the feasibility of installing sensors at different measuring points is analyzed to determine the optimal temperature monitoring point of the connecting rod bearing.

2. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 1, characterized in that: The dynamic substructure reduction is expressed as, ， ， ， ， ， in, , are the mass and stiffness matrices of the model respectively; , are displacement and force vectors, respectively; subscript , are the coordinates of the primary and secondary degrees of freedom, respectively; is the identity matrix; is the characteristic value; is the coordinate transformation matrix; for The transposed matrix of , , , are the mass model, stiffness matrix model and force vector model of the reduced model respectively. For the Order eigenvalue The value of .

3. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 2, characterized in that: The Greenwood / Tripp contact is represented by, ， ， when , when lubrication is in the rough contact area, ， when , that is, when lubrication is in the full lubrication zone, ， in, , , , are the elastic modulus and Poisson’s ratio of the journal and bearing respectively; is the equivalent elastic modulus; is the radius of curvature of the micro-convex peak; is the micro-convex peak density; is the gap thickness; , are the roughness of the journal and bearing surface respectively; is the comprehensive surface roughness.

4. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 3, characterized in that: The thermoelastic hydrodynamic lubrication theory is expressed as, ， in, and are the fluid dynamic pressure and the gap height; , , for , , The velocity of the fluid in the direction; , and They represent the circumferential coordinate, radial coordinate and axial coordinate of the bearing development respectively; and are the peripheral speeds of the bearing and journal, respectively; is the density of the oil; is the specific heat of the oil; It’s time; is the oil temperature; are the circular coordinates; is the gap height coordinate; is the thermal conductivity of the oil; is the axial velocity of the oil film; is the concave-convex contact pressure; is the boundary friction coefficient.

5. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 4, characterized in that: The simulation analysis includes calculating the load on the surface of the connecting rod bearing through a multi-body dynamics model, applying the load to the connecting rod bearing stress field model, and obtaining the connecting rod bearing stress through stress field simulation; For temperature field simulation, a single simulation is first performed. After multi-body dynamics simulation, the heat flux on the connecting rod bearing surface can be calculated. The temperature inside the crankcase of the marine engine is used as the boundary condition, and the heat flux on the connecting rod big end and small end bearing surfaces is used as the heat source. The temperature field simulation is carried out to obtain the connecting rod bearing temperature field and the bearing surface temperature profile. Based on the Matlab Simulink simulation platform, the multi-body dynamics model and the temperature field model are combined, and multiple iterative simulations are performed. The surface temperature profile of the connecting rod bearing of the n-1th simulation is used as the input of the nth simulation until the connecting rod bearing temperature field enters a steady state and the simulation is stopped.

6. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 5, characterized in that: The feasibility of analyzing the installation of sensors at different measuring point locations includes establishing a three-dimensional motion model based on the geometric models of the connecting rod, bearing, and crankshaft of the marine engine; In the three-dimensional motion model, the sensor geometry model is installed at different positions of the connecting rod, and the fixed antenna geometry model that receives the sensor signal is fixed; By observing the three-dimensional movement process of the marine engine, it is determined whether the sensor interferes with the fixed antenna, crankcase, and oil pan position, and the feasibility of installing the connecting rod bearing temperature measurement point is determined.

7. The engine connecting rod bearing temperature measurement point optimization method based on multi-physics fields as claimed in claim 6, characterized in that: Determining the optimal temperature monitoring point of the connecting rod bearing includes simulating and obtaining the temperature field and stress field of the connecting rod bearing under different operating conditions and different temperature measuring points of the marine engine; From the perspective of reliability, analyze the stress field to determine whether there is stress concentration at different measuring points; Analyze the temperature field and select the measuring points where the temperature change under different working conditions is greater than the preset threshold; The interference of connecting rod bearing temperature measuring points installed at different positions is analyzed through the three-dimensional motion model of the marine engine, and the measuring points without interference are selected; A comprehensive comparative analysis is carried out, and the measuring points where the stress change is less than the preset stress change threshold, the temperature change is greater than the preset temperature threshold and there is no interference are selected as the optimal temperature monitoring points for the connecting rod bearing.

8. A system using the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields as claimed in any one of claims 1 to 7, characterized in that: include: Preprocessing module, multi-body dynamics module for connecting rod bearings of marine engines, temperature field and stress field model building module, simulation module for connecting rod bearings of marine engines, feasibility analysis module for installation of temperature measuring points for connecting rod bearings of marine engines, and module for selecting the best temperature measuring points for connecting rod bearings of marine engines; The preprocessing module is used to obtain the structural data of the connecting rod, bearing and crankshaft of the marine engine, mesh the three-dimensional structure of the connecting rod, bearing and crankshaft of the marine engine, and perform dynamic substructure reduction; The marine engine connecting rod bearing multi-body dynamics module is used to establish a marine engine connecting rod bearing multi-body dynamics model based on Greenwood / Tripp contact and thermoelastic hydrodynamic lubrication theory, configure relevant parameters of the actual operation of the marine engine, perform multi-body dynamics simulation of the connecting rod assembly, and obtain the heat flow on the connecting rod bearing surface; The temperature field and stress field model building module is used to build a connecting rod bearing temperature field and stress field simulation model, and uses the heat flow and related boundary parameters on the connecting rod bearing surface as inputs of the temperature field simulation model to perform temperature field simulation; The load on the connecting rod bearing surface is used as the input of the stress field simulation model to perform stress field simulation; The marine engine connecting rod bearing simulation module is used to simulate and analyze the stress field and temperature field of the connecting rod bearing to obtain a three-dimensional diagram of the stress and temperature distribution of the bearing; The feasibility analysis module for installing the temperature measuring points of the connecting rod bearing of the marine engine is used to analyze the feasibility of installing the sensor at different measuring points in combination with the three-dimensional motion model of the marine engine; The module for selecting the optimal temperature measurement point of the connecting rod bearing of a marine engine is used to combine the temperature field, stress field and three-dimensional motion model of the connecting rod bearing, analyze the circumferential temperature profile of the bearing surface and the stress of the connecting rod, judge whether there is interference, and determine the optimal temperature monitoring point of the connecting rod bearing.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the engine connecting rod bearing temperature measurement point optimization method based on multi-physical fields described in any one of claims 1 to 7 are implemented.

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