Shafting design method and apparatus

Abstract

The application provides a shafting design method and device, and relates to the field of engines. The method comprises the following steps: establishing a shafting finite element model, obtaining load and deformation data of each shafting support point, identifying load concentration areas and deformation out-of-tolerance extreme position, and setting optimization thresholds of load deviation and deformation difference. The firing order is determined to achieve bearing load homogenization and avoid load superposition and shafting resonance. According to the firing order and shafting deformation law, the structural parameters of the crank arm corresponding to the maximum deformation area in the middle section of the shafting are adjusted. The non-load-bearing installation area on the left and right sides of the main bearing cover is locally weakened to form a flexible area. Based on the firing order, the structural parameters of the crank arm and the flexible area, simulation calculation is carried out, the structural parameters of the flexible area and the crank arm are iteratively adjusted, the concentrated load is redistributed along multiple support points of the shafting by using the adaptive micro-deformation of the crankshaft structure and the flexible area, and the optimization threshold is met.

Description

Technical Field

[0001] This invention relates to the field of engines, and more particularly to a shaft system design method and apparatus. Background Technology

[0002] Existing shaft system designs generally adopt a rigid design approach of thickening the crankshaft journal, thickening the engine block support structure, and enhancing overall rigidity. This provides a fully rigid structural support for the crankshaft system of high-power, high-load multi-cylinder diesel engines, and forcibly constrains the micro-deformation of the crankshaft.

[0003] This centralized load-bearing mode cannot achieve distributed load distribution. The rigid structure forcibly constrains the normal micro-deformation of the crankshaft, which can easily cause uneven load on the friction pair between the main bearing and the main journal, excessive local specific pressure, and easy rupture of the lubricating oil film. Long-term operation may lead to failures such as bearing erosion and abnormal wear.

[0004] Furthermore, the existing crankshaft structure design does not incorporate the deformation characteristics of slender shaft systems for directional optimization. The crankshaft deformation gradient is poorly matched with the engine block and main bearing caps. This, combined with the influence of the firing order, further exacerbates the uneven load distribution. Summary of the Invention

[0005] The purpose of this invention is at least to provide a shaft system design method and device, which, through the coupled and coordinated design of firing order, crankshaft axial gradient stiffness, and main bearing cover zoned flexibility, ensures that the local stiffness of the crankshaft and the support flexibility of the engine body form a coordinated response, reduces concentrated loads, non-uniform bending deformation, and alternating stress, and improves the operating stability of the engine shaft system, the overall reliability of the engine, and the service life of the components.

[0006] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0007] This invention provides a shaft system design method, comprising the following steps: Establish a finite element model of the integrated crankshaft and engine block system, conduct multi-condition simulations, obtain load and deformation data of each shaft support point, identify load concentration areas, extreme locations of deformation deviations, and resonance danger speed ranges, and set optimization thresholds for load deviation and bending deformation difference to achieve uniform load distribution at multiple support points. Based on the load concentration area, the extreme position of deformation deviation and the dangerous speed of resonance, and with the constraints of eliminating the superposition of transient loads at adjacent support points and balancing the load of all bearings, the firing sequence is determined by matching the axial deformation law of the slender shaft system. Differentiated matching of crankshaft stiffness gradient; adjustment of crank arm structural parameters corresponding to the maximum deformation area in the middle section of the shaft system. The non-load-bearing installation areas on both sides of the main bearing cover are locally weakened to create flexible zones. Using the firing order, crank arm structural parameters, and flexible zone as common inputs, the degree of weakening of the flexible zone and the crank arm structural parameters are adjusted synchronously and iteratively until the result meets the preset optimization thresholds for load deviation and bending deformation difference.

[0008] Another aspect of the present invention provides a shaft system design apparatus, comprising: The model analysis module is used to establish a finite element model of the integrated crankshaft system, conduct multi-condition simulations, obtain load and deformation data of each shaft support point, identify load concentration areas, extreme locations of deformation deviations and resonance danger speed ranges, and set optimization thresholds for load deviation and bending deformation difference to achieve uniform load distribution at multiple support points. The firing sequence determination module is used to determine the firing sequence based on the load concentration area, the extreme position of deformation deviation and the resonance danger speed, with the constraints of eliminating the superposition of transient loads at adjacent support points and the balance of bearing loads across the entire range, and matching the axial deformation law of the slender shaft system. The crank parameter adjustment module is used to differentiate and match the crankshaft stiffness gradient, and adjust the structural parameters of the crank arm corresponding to the maximum deformation area in the middle section of the shaft system. The flexible zone setting module is used to locally weaken the non-load-bearing installation areas on the left and right sides of the main bearing cover to form a flexible zone; The collaborative iteration module is used to synchronously and iteratively adjust the degree of weakening of the flexible area and the structural parameters of the crank arm, taking the firing order, crank arm structural parameters and flexible area as common inputs, and iterates until the result meets the preset optimization threshold of load deviation and bending deformation difference.

[0009] In another aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method described in the first aspect.

[0010] The shaft system design method proposed in this specification constructs a collaborative design system through multi-dimensional coupled design, such as firing order optimization, crank arm structural parameter adjustment, and local stiffness weakening of main bearing cap, to achieve the effect of load diversion and compliant bearing, and solve the problem of unstable operation of friction pairs in multi-cylinder slender shaft systems. Attached Figure Description

[0011] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related properties or features may have the same or similar reference numerals.

[0012] Figure 1 This is a schematic flowchart of a shaft system design method according to an embodiment of the present invention.

[0013] Figure 2 This is a schematic diagram of the modular structure of a shaft system design device according to an embodiment of the present invention.

[0014] Figure 3 This is a schematic diagram of the crankshaft.

[0015] Figure 4 This is a schematic diagram of the main bearing cover.

[0016] Figure 5 This is a schematic diagram of the crankshaft journal.

[0017] Figure 6 This is a schematic diagram of the spiral groove oil tank layout. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0019] It should be understood that the terms “system,” “device,” “unit,” and / or “module” used herein are one method of distinguishing different components, elements, parts, sections, or assemblies at different levels. However, if other words can achieve the same purpose, they may be replaced by other expressions.

[0020] Flowcharts are used in this specification to illustrate the operations performed by the system according to embodiments of this specification. It should be understood that the preceding or following operations are not necessarily performed in exact order. Instead, the steps can be processed in reverse order or simultaneously. Furthermore, other operations can be added to these processes, or one or more steps can be removed from them.

[0021] As indicated in this specification and claims, the words “a,” “an,” “an,” and / or “the” are not specifically singular and may include plural forms unless the context clearly indicates otherwise. Generally, the terms “comprising” and “including” only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0022] like Figure 1As shown, this embodiment provides a shaft system design method. This method takes the slender crankshaft system of a high-power, high-load multi-cylinder diesel engine as the design object. Through multi-dimensional collaborative design, including firing order optimization, crank arm structural parameter adjustment, and local stiffness weakening of the main bearing cap, it constructs a collaborative design logic encompassing firing order optimization, engine block crankshaft stiffness adaptation, and load flexible distribution, achieving load distribution, deformation complementarity, and lubrication enhancement. The method includes the following steps S1 to S5.

[0023] Step S1: Establish a finite element model of the integrated crankshaft-body system, conduct multi-condition simulation, obtain load and deformation data of each shaft support point, identify load concentration areas, extreme locations of deformation deviations and resonance danger speed ranges, and set optimization thresholds for load deviation and bending deformation difference to achieve uniform load distribution at multiple support points.

[0024] Specifically, based on the overall structural parameters of the diesel engine (including the number of cylinders, cylinder bore, V-angle, etc.) and the structural parameters of the engine block and crankshaft, an integrated finite element simulation model of the engine block and crankshaft is established. During the modeling process, various load boundary conditions, such as idling, rated operation, and overload conditions, are considered. Constraints between parts are set according to the actual assembly relationship of the diesel engine. Material mechanical property parameters are substituted to complete the model verification and ensure the accuracy of the simulation calculation.

[0025] Finite element method (FEM) simulations were used to extract load data such as radial and axial loads, as well as deformation data such as bending deformation, torsional vibration modes, and stress distribution data at each support point of the shaft system. Based on this data, areas of concentrated loads, locations of extreme deformation deviations, and resonance-critical speed ranges were marked.

[0026] Setting optimization thresholds for load concentration areas and extreme deformation deviation locations includes: the maximum load deviation in load concentration areas (such as the main support position of adjacent shafts) should not exceed 5%, and the bending deformation difference of each support point should be controlled within the preset design threshold.

[0027] In this step, by establishing an integrated finite element model and conducting simulation analysis, we can fully understand the load distribution characteristics and deformation laws of the shaft system under working conditions, providing a data basis for subsequent firing sequence optimization, crank arm structural parameter adjustment, and main bearing cap local stiffness weakening design.

[0028] Step S2: Based on the load concentration area, the extreme position of deformation deviation and the resonant danger speed, and with the constraints of eliminating the superposition of transient loads at adjacent support points and balancing the load of all bearings, the firing sequence is determined by matching the axial deformation law of the slender shaft system.

[0029] Based on obtaining load and deformation data of each support point of the shaft system in step S1, identifying load concentration areas, extreme locations of deformation exceeding tolerance, and dangerous speed ranges of resonance, the firing sequence is optimized with the goal of uniformizing the load of each bearing and avoiding load superposition and shaft resonance.

[0030] For inline multi-cylinder slender shaft systems, an alternating firing pattern is employed. Specifically, the firing sequence is designed so that adjacent cylinders fire discontinuously, meaning there is at least one unfired cylinder between two adjacent cylinders. This disperses the instantaneous burst load along the axial space, preventing adjacent support points from bearing superimposed loads at the same time. For example, for an inline six-cylinder diesel engine, a firing sequence of 1-5-3-6-2-4 can be used, ensuring a uniform firing interval angle between adjacent cylinders and effectively reducing load concentration.

[0031] For V-type multi-cylinder slender shaft systems, a staggered firing method for the left and right rows of cylinders is adopted. Specifically, the firing times of the left and right rows of cylinders are staggered by a certain crankshaft angle, so that the combustion loads of the left and right rows of cylinders do not overlap at the same time, balancing the lateral load and reducing the lateral vibration and load offset of the shaft system. For example, for a V-type twelve-cylinder diesel engine, the firing interval angle of the corresponding cylinders in the left and right rows can be set to a crankshaft angle of 60°, so that the load is evenly distributed in both the lateral and longitudinal directions.

[0032] The slender shaft system referred to in this invention refers to rotating shaft parts and related systems in an engine with a large length-to-diameter ratio (the ratio of the shaft's length to its diameter) (e.g., greater than 20).

[0033] After optimizing the firing sequence, simulation verification was carried out again to confirm that there was no load superposition under rated and overload conditions, and that the shaft system operated outside the resonance danger speed range without resonance.

[0034] Step S3: Differentiate the crankshaft stiffness gradient and adjust the structural parameters of the crank arm corresponding to the maximum deformation area in the middle section of the shaft system.

[0035] After determining the firing order in step S2, and combining the deformation patterns of the slender shaft system obtained in step S1, a differentiated crank arrangement design is carried out. For example... Figure 3 As shown, for the maximum deformation area (i.e. the area with the largest deformation) 31 in the middle section of the shaft system, the width and thickness of the crank arm of the corresponding crankshaft are adjusted to increase the local stiffness of the crankshaft and reduce the bending deformation in this area.

[0036] Specifically, under the action of combustion gas pressure and reciprocating inertial force, the mid-section support of the shaft system experiences the greatest bending deformation due to the combined effect of the excitation loads from the adjacent multiple cylinders on both sides. By increasing the width of the crank arm corresponding to the maximum deformation area 31 in the mid-section (i.e., increasing the extension dimension of the crank arm along the crankshaft axis) and simultaneously increasing the thickness of the crank arm (i.e., increasing the cross-sectional height of the crank arm along the crankshaft radially), the bending section modulus of the crankshaft in this area can be increased, thereby enhancing the local bending stiffness.

[0037] It is important to note that the support areas 32 at both ends of the shaft system retain the original crankshaft structure and stiffness. Compared to the mid-section support position, the two ends of the shaft system are only subjected to the load of the adjacent cylinder on one side, resulting in smaller deformation. Maintaining the original crankshaft structure is sufficient to meet the load-bearing requirements, without the need for additional reinforcement. This differentiated design creates a reasonable gradient distribution of crankshaft stiffness along the axial direction, with enhanced stiffness in the mid-section to suppress maximum deformation, and the original stiffness maintained at both ends to avoid unnecessary mass increases.

[0038] Step S4: Locally weaken the non-load-bearing installation areas on both sides of the main bearing cover to form flexible zones.

[0039] After adjusting the crank arm structural parameters in step S3, further design steps are taken to weaken the local stiffness of the main bearing cap. Specifically, the non-load-bearing mounting areas on the left and right sides of the main bearing cap are designated as optimization areas, such as... Figure 4 As shown, the structure of this area is locally weakened to form a gradient flexible zone 41. At the same time, the bearing bush fitting area 42 in the middle of the main bearing cover and the main bolt connection area 43 maintain their original structure, dimensions and rigidity.

[0040] The main bearing cap bears radial loads from the crankshaft during operation, primarily transmitted through the central bearing bush mating area 42. This central bearing bush mating area 42 is the core load-bearing region of the main bearing cap, and its structural integrity and rigidity directly affect the bearing bush support accuracy and the mating clearance of the friction pair. The main bolt connection area 43 secures the main bearing cap to the engine block via main bolts, and its structural strength directly impacts the reliability of the main bearing cap's fastening. Therefore, both of these areas must maintain their original structure, dimensions, and rigidity without any weakening.

[0041] The non-load-bearing installation areas on the left and right sides of the main bearing cover do not directly bear the main load in the working state. The gradient flexible area 41 formed by locally weakening the structure of this area can generate controllable micro-deformation when the shaft system bears concentrated load, so that the concentrated load is diverted to the adjacent support point through the micro-deformation of the flexible area, thereby realizing the redistribution of the load.

[0042] In some embodiments, the gradient flexible region 41 is formed by one or at least a combination of the following: Method 1: Symmetrically create grooves in the non-load-bearing mounting areas on both sides of the main bearing cover (e.g., Figure 4 The groove in the gradient flexible zone 41 is shown. The groove can have an arc or rectangular cross-section, and the corners of the groove are machined with rounded transitions to eliminate stress concentration caused by abrupt changes in stiffness. By adjusting the depth, width, and position of the groove, the degree of stiffness reduction in the flexible zone can be controlled. The symmetrical arrangement ensures that the stiffness of the left and right sides of the main bearing cap is symmetrical, avoiding load offset.

[0043] Method 2: Symmetrically and uniformly thin the sidewalls on both sides of the main bearing cap. Precision machining is used to uniformly reduce the thickness of the sidewalls by a certain amount, achieving a controllable decrease in local stiffness. The amount of thinning is determined based on the shaft load characteristics and deformation requirements, ensuring sufficient flexibility for load distribution while avoiding excessive thinning that could lead to insufficient structural strength.

[0044] Method 3: A composite structure combining Method 1 and Method 2 is used to form a gradient flexibility zone 41. This composite structure is suitable for high-power, heavy-duty, long shaft systems, and achieves more precise stiffness gradient control through the synergistic effect of the two weakening methods.

[0045] Step S5: Using the firing order, crank arm structural parameters, and flexible zone as common inputs, synchronously iterate and adjust the degree of weakening of the flexible zone and the crank arm structural parameters until the result meets the preset optimization threshold of load deviation and bending deformation difference.

[0046] After completing the firing order optimization in step S2, the crank arm structural parameter adjustment in step S3, and the main bearing cover flexible area setting in step S4, multi-condition simulation calculations are carried out based on the optimized firing order, crank arm structural parameters, and main bearing cover flexible area structure to obtain the load and deformation data of each main support point.

[0047] The simulation results are compared with the optimization thresholds set in step S1 to determine whether the maximum load deviation at the main support positions of adjacent shaft sections does not exceed 5% and whether the bending deformation difference at each support point is controlled within the preset design threshold. If the optimization thresholds are not met, the structural parameters of the flexible zone and crank arm are iteratively adjusted.

[0048] Specifically, the parameters adjusted iteratively include: the dimensions of the main bearing cap groove (including groove depth, width, and location) and / or sidewall thickness, as well as the width and thickness of the crank arm. In each iteration, the parameters of the corresponding regions are adjusted in a targeted manner based on the load concentration areas and extreme deformation deviation locations identified in the simulation feedback. If the load at a certain support point is still too high, increase the degree of stiffness weakening of the flexible area on both sides of the main bearing cap corresponding to that support point (such as increasing the groove depth or reducing the sidewall thickness) to enhance the flexible deformation capacity at that location and allow more concentrated loads to be diverted to adjacent support points. If the bending deformation in a certain area still exceeds the tolerance, increase the width and thickness of the corresponding crank arm in that area to improve local stiffness and suppress deformation. If the load distribution tends to be uniform but the deformation deviation is large at some locations, the combination of crank arm structural parameters and flexible zone parameters is fine-tuned to make the stiffness gradient more matched with the load distribution.

[0049] By utilizing the adaptive micro-deformation of the crankshaft structure and the flexible zones on both sides of the main bearing cap, concentrated loads at single points are diverted, allowing the load to be redistributed along multiple support points of the shaft system, thus completing the distributed load distribution. This process is iterated repeatedly until the load and deformation indicators meet the preset optimization thresholds.

[0050] The core principle of this step lies in the adaptive micro-deformation of the flexible zone, which enables the main bearing cap to generate controllable elastic deformation under concentrated loads. This transfers part of the load, originally concentrated at a single support point, to adjacent support points, achieving a redistribution of the load along multiple support points of the shaft system. Simultaneously, differentiated adjustments to the crank arm structural parameters match the crankshaft stiffness gradient with the load distribution pattern, further optimizing the load distribution effect.

[0051] After completing the firing order optimization, crank arm structural parameter adjustment, main bearing cap flexible zone setting, and collaborative iterative simulation in steps S1 to S5, a shallow surface machining process is further performed on the outer cylindrical surfaces of the main bearing journal and connecting rod journal based on the load distribution characteristics of each journal. This process forms a microstructure to optimize the lubrication performance of the friction pair. All of the above microstructures are shallow surface machining and will not change the crankshaft base dimensions or overall structural strength.

[0052] In some embodiments, the microstructure includes microtexture. For example, laser processing techniques, such as... Figure 5 As shown, circular or elliptical oil-retaining micro-pits are machined in the high-pressure load-bearing zone 51. The diameter of the micro-pits ranges from 0.3 mm to 1.0 mm, and the depth ranges from 0.02 mm to 0.08 mm. Machining these micro-pits in the high-pressure load-bearing zone 51 can create a secondary lubrication source during the operation of the friction pair. When the lubricating oil film thins locally due to load fluctuations, the lubricating oil stored in the micro-pits can be replenished to the friction surface in a timely manner, maintaining oil film stability. For example, guiding micro-grooves can be arranged in the transition zone to guide the lubricating oil from the high-pressure zone to the low-pressure zone, improving the uniformity of lubricating oil distribution on the journal surface.

[0053] In other embodiments, the microstructure includes a rough surface. Specifically, precision grinding is used in segments to control the surface roughness Ra of the high-pressure load-bearing region 51 to 0.1 μm to 0.2 μm, reducing frictional resistance and minimizing power consumption and heat generation of the friction pair under high loads. The surface roughness Ra of the edge non-load-bearing region 52 is controlled to 0.4 μm to 0.8 μm, utilizing the higher surface roughness to achieve oil storage and guiding functions, forming a micro-oil pool in the non-load-bearing region 52, and improving the retention capacity of lubricating oil on the journal surface. Through differentiated roughness design in different areas of the same journal surface, zonal optimization of lubrication performance is achieved.

[0054] In some other embodiments, such as Figure 6 As shown, the microstructure includes spiral grooves 61. Specifically, combined with... Figure 5 and Figure 6 Shallow spiral groove oil grooves 61 are machined in the high-pressure load zone 51, with a groove depth not exceeding 0.1 mm, using ultrasonic elliptical vibration cutting technology. The rotation direction of the spiral grooves is opposite to that of the crankshaft. When the crankshaft rotates, the spiral grooves create a spiral pump effect, uniformly distributing the lubricating oil in the bearing clearance along the groove axis, improving the axial transport capacity of the lubricating oil. In addition, the small amount of lubricating oil stored in the spiral grooves forms oil reservoir lubrication before the oil film is established at start-up and shutdown times, improving cold start lubrication performance and reducing dry friction wear during start-up and shutdown.

[0055] The above three microstructures can be used individually or in combination, depending on the load distribution characteristics of each journal, to meet the lubrication requirements of different journals under different working conditions.

[0056] After completing the above simulation optimization design, based on the determined firing order, crank arm structural parameters, main bearing cap flexible area structural dimensions, and journal microstructure, the parts were prototyped and assembled, and multi-condition bench tests were conducted for verification. The bench tests included torsional vibration testing, performance testing, and component wear detection, assessing key indicators such as the overall machine's torsional vibration characteristics, bearing wear condition, and operational stability.

[0057] By combining simulation data and bench test results, the firing sequence, crank arrangement parameters, main bearing cap softening structure dimensions, and journal microstructure parameters were solidified, and the design was finalized. Through cross-validation of simulation and experiment, the effectiveness of the design under actual working conditions was ensured, ultimately resulting in a shaft system collaborative design scheme that meets the optimization thresholds for load deviation and deformation difference.

[0058] Based on the above method, embodiments of this specification also provide a shaft system design device. For example... Figure 2 As shown, the device includes a model analysis module, an firing order determination module, a crank parameter adjustment module, a flexible zone setting module, and a collaborative iteration module.

[0059] The model analysis module is used to perform step S1 in the above method.

[0060] The firing order determination module is used to perform step S2 in the above method.

[0061] The crank parameter adjustment module is used to perform step S3 in the above method.

[0062] The flexible area setting module is used to perform step S4 in the above method.

[0063] The collaborative iteration module is used to execute step S5 in the above method.

[0064] The modules described above can be integrated into the same computing device or distributed across different computing nodes as needed, with information exchange between modules achieved through data interfaces. The specific implementation of each module may include hardware circuits, firmware, software, or a combination thereof.

[0065] This specification also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described shaft system design method.

[0066] Specifically, the computer program includes the following instructions: instructions to establish a finite element model of the shaft system and obtain load and deformation data for each support point; instructions to determine the firing sequence with the goal of uniformizing bearing load and avoiding load superposition and shaft resonance; instructions to adjust the crank arm structural parameters according to the firing sequence and shaft deformation law; instructions to locally weaken the non-load-bearing installation areas on the left and right sides of the main bearing cap to form a flexible zone; and instructions to perform simulation calculations and iterative adjustments based on the firing sequence, crank arm structural parameters, and flexible zone until the optimization threshold is met.

[0067] Computer-readable storage media may include, but are not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks, and other media capable of storing program code.

[0068] The collaborative design method proposed in this specification is applicable to the slender shaft system of high-power, high-load multi-cylinder diesel engines. Through multi-dimensional coupled design, such as firing order optimization, crank arm structural parameter adjustment, local stiffness weakening of main bearing cap, and journal micromorphology design, a collaborative design system is constructed to achieve the effect of load diversion and compliant bearing, and solve the problem of unstable operation of friction pairs in multi-cylinder slender shaft systems.

[0069] It also proposes a differentiated structural design with strong load-bearing capacity in the middle and flexible compensation on both sides of the main bearing cover. By setting gradient flexible zones in the non-load-bearing installation areas on the left and right sides of the main bearing cover, the adaptive micro-deformation of the flexible zones is used to complete the load diversion and redistribution, so that the load and deformation height of the multiple support points of the shaft system are uniform, realizing the distributed load diversion and bearing, and effectively solving the problems of friction pair eccentric load and edge wear.

[0070] Furthermore, differentiated crankshaft structure schemes and main bearing cap structure schemes with weakened local stiffness were proposed. These schemes can achieve a balance between crankshaft stiffness gradient, engine block support, and flexible deformation of the main bearing cap, effectively compensating for bending deformation of slender shaft systems, significantly reducing alternating stress in the shaft system, and improving operational reliability. Simultaneously, through differentiated crankshaft arrangement design, the width and thickness of the crank arms are adjusted for the area with the largest deformation in the middle section of the shaft system, appropriately increasing the local stiffness of the crankshaft to reduce bending deformation, while the original crankshaft structure and stiffness are maintained in the support areas at both ends of the shaft system, achieving a reasonable distribution of stiffness gradient.

[0071] Furthermore, a microstructure structure for crankshaft journal surfaces suitable for slender shaft systems is proposed. Based on the load distribution characteristics of each journal, shallow surface processing is performed on the outer cylindrical surfaces of the main journal and connecting rod journal, including structures such as microtexture, gradient roughness, or shallow spiral micro-oil grooves, to optimize the lubrication performance of the friction pair and improve the stability of the lubricating oil film and cold start lubrication performance.

[0072] The basic concepts have been described above. It is clear that the detailed disclosure above is merely illustrative and does not constitute a limitation of this specification, especially for those skilled in the art. Furthermore, unless expressly stated in the claims, the order of elements and sequences, the use of numbers and letters, or other names in this specification are not intended to limit the order of the processes and methods described herein. Although various examples of currently considered useful embodiments of the invention have been discussed in the foregoing disclosure, it should be understood that such details are for illustrative purposes only, and the appended claims are not limited to the disclosed embodiments. Rather, the claims are intended to cover all modifications and equivalent combinations that conform to the substance and scope of the embodiments described herein.

Claims

1. A shaft system design method, characterized in that, Includes the following steps: Establish a finite element model of the integrated crankshaft and engine block system, conduct multi-condition simulations, obtain load and deformation data of each shaft support point, identify load concentration areas, extreme locations of deformation deviations, and resonance danger speed ranges, and set optimization thresholds for load deviation and bending deformation difference to achieve uniform load distribution at multiple support points. Based on the load concentration area, the extreme position of the deformation deviation and the resonance danger speed, and with the constraints of eliminating the superposition of transient loads at adjacent support points and balancing the loads of all bearings, the firing sequence is determined by matching the axial deformation law of the slender shaft system. Differentiated matching of crankshaft stiffness gradient; adjustment of crank arm structural parameters corresponding to the maximum deformation area in the middle section of the shaft system. The non-load-bearing installation areas on both sides of the main bearing cover are locally weakened to create flexible zones. Using the firing order, the structural parameters of the crank arm, and the flexible region as common inputs, the weakening degree of the flexible region and the structural parameters of the crank arm are adjusted synchronously and iteratively until the result satisfies the preset optimization threshold of the load deviation and the bending deformation difference.

2. The shaft system design method according to claim 1, characterized in that, The determination of the firing order includes: the inline multi-cylinder slender shaft system adopts an alternating firing method with each cylinder firing alternately.

3. The shaft system design method according to claim 1, characterized in that, The determination of the firing order includes: the V-type multi-cylinder slender shaft system adopts a staggered firing method for the left and right rows of cylinders.

4. The shaft system design method according to claim 1, characterized in that, The structural parameters of the crank arm corresponding to the maximum deformation area in the middle section of the shaft system include: adjusting the width and thickness of the crank arm, while maintaining the original crank structure and stiffness of the support areas at both ends of the shaft system.

5. The shaft system design method according to claim 1, characterized in that, The method of locally weakening the non-load-bearing installation areas on the left and right sides of the main bearing cover includes: processing the non-load-bearing installation areas into gradient flexible areas with gradually decreasing stiffness towards the outside, while maintaining the structure, size, and stiffness of the bearing bush fitting area and the main bolt connection area in the middle of the main bearing cover.

6. The shaft system design method according to claim 5, characterized in that, The gradient flexible region is formed by one or at least a combination of the following methods: Grooves are symmetrically formed in the non-load-bearing mounting areas on both sides of the main bearing cover. The side walls on both sides of the main bearing cover are symmetrically and uniformly thinned.

7. The shaft system design method according to claim 6, characterized in that, The iterative adjustment of the degree of weakening of the flexible area and the structural parameters of the crank arm includes: iteratively adjusting the size of the groove, including the opening position, depth, width, and / or the thinning thickness of the sidewall, as well as the width and thickness of the crank arm.

8. The shaft system design method according to claim 1, characterized in that, Also includes: Based on the load distribution characteristics of each journal, shallow surface machining is performed on the outer cylindrical surface of the main journal and connecting rod journal to form a microstructure.

9. The shaft system design method according to claim 8, characterized in that, The microstructure includes one or more combinations of oil storage microtexture, zoned differentiated rough surface, and reverse spiral groove oil channels.

10. A shaft system design device, characterized in that, include: The model analysis module is used to establish a finite element model of the integrated crankshaft system, conduct multi-condition simulations, obtain load and deformation data of each shaft support point, identify load concentration areas, extreme locations of deformation deviations and resonance danger speed ranges, and set optimization thresholds for load deviation and bending deformation difference to achieve uniform load distribution at multiple support points. The firing sequence determination module is used to determine the firing sequence based on the load concentration area, the extreme position of the deformation deviation and the resonance danger speed, with the constraints of eliminating the superposition of transient loads at adjacent support points and the balance of bearing loads across the entire range, and matching the axial deformation law of the slender shaft system. The crank parameter adjustment module is used to differentiate and match the crankshaft stiffness gradient, and adjust the structural parameters of the crank arm corresponding to the maximum deformation area in the middle section of the shaft system. The flexible zone setting module is used to locally weaken the non-load-bearing installation areas on the left and right sides of the main bearing cover to form a flexible zone; as well as The collaborative iteration module is used to synchronously and iteratively adjust the degree of weakening of the flexible region and the structural parameters of the crank arm, taking the firing order, the structural parameters of the crank arm and the flexible region as common inputs, and iterates until the result meets the preset optimization threshold of the load deviation and the bending deformation difference.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 9.

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