Design method of crankshaft assembly, crankshaft assembly and engine

Abstract

The invention relates to a design method of a crankshaft assembly, the crankshaft assembly and an engine. The design method comprises the steps that a crankshaft assembly three-dimensional model is established according to user demand information data; calculating crankshaft deformation according to the crankshaft working parameters; calculating oil film thickness distribution between the crankshaft and the bearing bush under all working conditions, judging whether the minimum oil film thickness Hmin is not less than a preset thickness and whether the oil film thickness uniformity coefficient H is not greater than a first preset coefficient, if so, entering the next step, and if not, returning to the first step for optimization; and calculating whether the thickness uniformity coefficient H of the oil film between the crankshaft and the bearing bush under the common working condition is not greater than a second preset coefficient and the second preset coefficient is less than the first preset coefficient, if so, finishing the design, and if not, returning to the first step for optimization. The design method can reduce the failure rate of the crankshaft assembly, improve the reliability of the crankshaft assembly, and meet the requirements of customers for long service life and high reliability of the engine.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and in particular to a design method of a crankshaft assembly, a crankshaft assembly and an engine. Background Art

[0002] The crankshaft is the core component of the engine for outputting torque to the outside, and it is required to operate stably throughout the engine's life cycle. As the engine's explosion pressure continues to increase, the load on the crankshaft has increased significantly, especially in supporting fields such as agricultural machinery, where the front or rear end of the engine needs to be connected to the load, resulting in more stringent forces on the crankshaft. Under this usage boundary, the wear problem of the crankshaft and bearings poses a great challenge to the reliability of the engine system, and even short-mileage main bearing failures may occur. Summary of the invention

[0003] The first object of the present invention is to provide a design method for a crankshaft assembly to improve the crankshaft-bearing reliability of a high explosion pressure, multi-load engine and meet customer demands for long engine life and high reliability.

[0004] A second object of the present invention is to provide a crankshaft assembly and an engine based on the above crankshaft assembly design method.

[0005] To achieve the above object, the present invention provides the following technical solutions: A design method for a crankshaft assembly, the crankshaft assembly comprising a crankshaft and a bearing, the design method comprising: S1: Obtain user demand information data, determine the initial structural dimensions of the crankshaft and the bearing according to the user demand information data, and establish a three-dimensional model; S2: Calculate the crankshaft deformation according to the crankshaft working parameters; S3: Calculate the oil film thickness distribution between the crankshaft and the bearing under all working conditions based on the three-dimensional model and the crankshaft deformation, and determine the minimum oil film thickness H min Whether the thickness is not less than the preset thickness, and whether the oil film thickness uniformity coefficient H is not greater than the first preset coefficient, if yes, then enter S4, if not, then return to S1 to optimize the structural dimensions of the crankshaft and the bearing; S4: Calculate the oil film thickness uniformity coefficient H between the crankshaft and the bearing under normal working conditions based on the three-dimensional model and the crankshaft deformation to see whether it is not greater than a second preset coefficient, and the second preset coefficient is less than the first preset coefficient. If so, the design is completed; if not, return to S1 to optimize the structural dimensions of the crankshaft and the bearing.

[0006] In one embodiment of the present application, S1 includes: S101: Acquire and analyze user application scenario information; S102: selecting a typical road spectrum and a corresponding front-end and rear-end output structure of the engine according to the user application scenario information; S103: Determine the initial structural dimensions of the crankshaft and the bearing according to the selected typical road spectrum and the corresponding front and rear end output structures of the engine, and establish a three-dimensional model.

[0007] In one embodiment of the present application, the crankshaft operating parameters in S2 include the front and rear end loads, rotation speed, torque and engine cylinder pressure of the crankshaft.

[0008] In one embodiment of the present application, the calculation method of the oil film thickness uniformity coefficient H in S3 and S4 is: Among them, H max is the maximum oil film thickness, H average It is the average oil film thickness between the crankshaft and the bearing.

[0009] In one embodiment of the present application, the preset thickness is 1 μm.

[0010] In one embodiment of the present application, the first preset coefficient is 0.3.

[0011] In one embodiment of the present application, the second preset coefficient is 0.2.

[0012] A crankshaft assembly is designed using the crankshaft assembly design method as described in any one of the above.

[0013] In one embodiment of the present application, in the axial direction of the crankshaft of the crankshaft assembly, the diameter of the middle portion of the main journal of the crankshaft is larger than the diameters of the two ends of the main journal, and / or the diameter of the middle portion of the connecting rod journal of the crankshaft is larger than the diameters of the two ends of the connecting rod journal; In the axial direction of the crankshaft of the crankshaft assembly, the wall thickness of the middle portion of the bearing shell is greater than the wall thickness of the two ends of the bearing shell.

[0014] An engine comprises a crankshaft assembly, wherein the crankshaft assembly is the crankshaft assembly as described above.

[0015] It can be seen from the above technical scheme that the present invention discloses a design method for a crankshaft assembly, which includes: S1: obtaining user demand information data, determining the initial structural dimensions of the crankshaft and the bearing according to the user demand information data, and establishing a three-dimensional model; S2: calculating the crankshaft deformation according to the crankshaft working parameters; S3: calculating the oil film thickness distribution between the crankshaft and the bearing under all working conditions according to the three-dimensional model and the crankshaft deformation, and determining the minimum oil film thickness H minWhether it is not less than the preset thickness, and whether the oil film thickness uniformity coefficient H is not greater than the first preset coefficient. If so, enter S4; if not, return to S1 to optimize the structural dimensions of the crankshaft and the bearing; S4: Calculate whether the oil film thickness uniformity coefficient H between the crankshaft and the bearing under common working conditions is not greater than the second preset coefficient based on the three-dimensional model and the crankshaft deformation, and the second preset coefficient is less than the first preset coefficient. If so, the design is completed; if not, return to S1 to optimize the structural dimensions of the crankshaft and the bearing.

[0016] The above-mentioned crankshaft assembly design method can be designed accordingly according to user needs in combination with the crankshaft load and the front and rear end loads of the engine, optimize the structural dimensions of the crankshaft and the bearing, so that the deformation of the crankshaft during high-speed operation compensates for the gap between the crankshaft and the bearing, maintains a good oil film thickness and oil film uniformity between the crankshaft and the bearing, thereby reducing the wear of the crankshaft and the bearing, reducing the failure rate of the crankshaft assembly, and improving the reliability of the crankshaft assembly of high explosion pressure and multi-load engines, meeting customers' needs for long engine life and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart of a method for designing a crankshaft assembly provided by one embodiment of the present invention; Figure 2 A flow chart of a method for designing a crankshaft assembly provided in accordance with another embodiment of the present invention; Figure 3 A schematic structural diagram of a crankshaft assembly provided in an embodiment of the present invention.

[0019] In the figure: 100 is the crankshaft; 110 is the main journal; 200 is the bearing. DETAILED DESCRIPTION

[0020] One of the cores of the present invention is to provide a design method for a crankshaft assembly, which can improve the crankshaft-bearing reliability of high explosion pressure and multi-load engines and meet customers' needs for long engine life and high reliability.

[0021] Another core of the present invention is to provide a crankshaft assembly and an engine based on the above-mentioned crankshaft assembly design method.

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1 , Figure 1 A flow chart of a method for designing a crankshaft assembly provided in accordance with an embodiment of the present invention.

[0024] An embodiment of the present invention discloses a method for designing a crankshaft assembly, and the method for designing a crankshaft assembly includes: S1: Obtain user demand information data, determine the initial structural dimensions of the crankshaft 100 and the bearing shell 200 according to the user demand information data, and establish a three-dimensional model.

[0025] User demand information includes the user's application scenario, whether there is load on the front and back ends of the engine, etc.

[0026] S2: Calculate the crankshaft deformation according to the crankshaft working parameters.

[0027] S3: Calculate the oil film thickness distribution between the crankshaft 100 and the bearing 200 under all working conditions based on the three-dimensional model and the crankshaft deformation, and determine the minimum oil film thickness H min Whether it is not less than the preset thickness and whether the oil film thickness uniformity coefficient H is not greater than the first preset coefficient, if it is satisfied, enter S4, if not, return to S1 to optimize the structural dimensions of the crankshaft 100 and the bearing shell 200.

[0028] A multi-body dynamics calculation model is built using EXCITE PU software to calculate the above oil film thickness distribution. During the calculation, the crankshaft part corresponding to each cylinder of the engine must be calculated.

[0029] In a specific embodiment of the present application, the preset thickness is 1 μm, that is, it is necessary to ensure that H min ≥1μm.

[0030] S4: Calculate the oil film thickness uniformity coefficient H between the crankshaft 100 and the bearing 200 under normal working conditions based on the three-dimensional model and the crankshaft deformation to see whether it is not greater than a second preset coefficient, and the second preset coefficient is less than the first preset coefficient. If so, the design is completed; if not, return to S1 to optimize the structural dimensions of the crankshaft 100 and the bearing 200.

[0031] Engine operating conditions refer to the state of the engine operating under different conditions. The engine mainly includes the following five operating conditions.

[0032] One is the starting condition, that is, the engine starts running from a stationary state. Under this condition, the engine needs to supply an extremely rich mixture to ensure smooth starting.

[0033] The second is the idle condition, that is, the state where the engine is running under no load or very small load. At this time, the engine should also supply a richer mixture to maintain stable idle operation.

[0034] The third is the medium load condition. When the engine needs to output a certain amount of power to drive the vehicle, it enters the medium load condition. Under this condition, the mixture supplied by the engine is relatively lean in order to achieve better fuel economy and power output.

[0035] The fourth is the high load / full load condition. When the vehicle needs to accelerate, climb a slope or perform other operations that require high power output, the engine enters the high load or full load condition. Under this condition, the engine needs to supply more and richer mixture to obtain maximum power.

[0036] The fifth is the acceleration condition. The process of increasing the vehicle's driving speed in a short period of time is called the acceleration condition. At this time, the engine's output power increases rapidly, and additional fuel supply is required to instantly enrich the mixture to meet the acceleration needs.

[0037] Therefore, when calculating the oil film thickness distribution between the crankshaft 100 and the bearing bush 200 under all working conditions, it is necessary to consider the situation where the engine is running at full load and the crankshaft deformation is the largest. At this time, the maximum oil film thickness H between the crankshaft 100 and the bearing bush 200 is max Minimum oil film thickness H between crankshaft 100 and bearing 200 min The difference between them is the largest, so in this application the first preset coefficient is 0.3, that is, in S3, H≤0.3, and under normal circumstances the load of the engine's normal operating conditions is less than the engine's full load, at this time the crankshaft deformation is relatively small, so in this application the second preset coefficient is 0.2, that is, in S4, H≤0.2.

[0038] Compared with the prior art, the design method of the crankshaft assembly provided in the embodiment of the present invention can be designed accordingly according to user needs in combination with the crankshaft load and the front and rear end loads of the engine, optimize the structural dimensions of the crankshaft 100 and the bearing 200, so that the deformation of the crankshaft 100 during high-speed operation compensates for the gap between the crankshaft 100 and the bearing 200, maintains a good oil film thickness and oil film uniformity between the crankshaft 100 and the bearing 200, thereby reducing the wear of the crankshaft 100 and the bearing 200, reducing the failure rate of the crankshaft assembly, and improving the reliability of the crankshaft assembly of high explosion pressure and multi-load engines, meeting customer needs for long engine life and high reliability.

[0039] Specifically, in one embodiment of the present application, S1 includes: S101: Acquire and analyze user application scenario information.

[0040] That is, to determine the engine for which the crankshaft assembly to be designed will be used.

[0041] S102: Select a typical road spectrum and a corresponding engine front-end and rear-end output structure according to user application scenario information.

[0042] A typical road spectrum refers to testing of parameters such as dynamic stress, driving resistance, and six-component wheel force that a vehicle is subjected to under different road conditions, in order to evaluate the vehicle's performance under different road conditions. The front and rear end output structure of the engine mainly depends on its layout. Common layouts include front-mounted front-wheel drive, front-mounted rear-wheel drive, rear-mounted rear-wheel drive, and mid-mounted rear-wheel drive.

[0043] S103: Determine the initial structural dimensions of the crankshaft 100 and the bearing 200 according to the selected typical road spectrum and the corresponding front and rear end output structures of the engine, and establish a three-dimensional model.

[0044] It should be noted that the crankshaft operating parameters in S2 include the front and rear end loads, speed, torque and engine cylinder pressure of the crankshaft.

[0045] In one embodiment of the present application, the calculation method of the oil film thickness uniformity coefficient H in S3 and S4 is: Among them, H max is the maximum oil film thickness, H average It is the average oil film thickness between the crankshaft 100 and the bearing 200.

[0046] An embodiment of the present application also provides a crankshaft assembly, which is a crankshaft assembly designed using the design method of the crankshaft assembly described in the above embodiment. Since the crankshaft assembly is designed using the above design method, please refer to the above embodiment for the technical effect of the crankshaft assembly.

[0047] like Figure 3 As shown, in a specific embodiment of the present application, in the axial direction of the crankshaft 100 of the crankshaft assembly, the diameter of the middle portion of the main journal 110 of the crankshaft 100 is larger than the diameter at both ends of the main journal 110, and / or the diameter of the middle portion of the connecting rod journal (not shown in the figure) of the crankshaft 100 is larger than the diameter at both ends of the connecting rod journal, that is, only the diameter of the middle portion of the main journal 110 of the crankshaft 100 may be larger than the diameter at both ends of the main journal 110, or only the diameter of the middle portion of the connecting rod journal of the crankshaft 100 may be larger than the diameter at both ends of the connecting rod journal, or the diameter of the middle portion of the connecting rod journal of the crankshaft 100 may be larger than the diameter at both ends of the connecting rod journal, and the diameter of the middle portion of the connecting rod journal of the crankshaft 100 is larger than the diameter at both ends of the connecting rod journal.

[0048] Accordingly, in the axial direction of the crankshaft 100 of the crankshaft assembly, the wall thickness of the middle portion of the bearing shell 200 is greater than the wall thickness of both ends of the bearing shell 200 .

[0049] An embodiment of the present application also provides an engine, which includes a crankshaft assembly, and the crankshaft assembly is the crankshaft assembly as described in the above embodiment. Since the crankshaft assembly of the engine is designed using the above design method, the technical effects of the engine should also refer to the above embodiment.

[0050] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0051] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for designing a crankshaft assembly, the crankshaft assembly comprising a crankshaft (100) and a bearing (200), characterized in that: The design method comprises: S1: obtaining user demand information data, determining the initial structural dimensions of the crankshaft (100) and the bearing (200) according to the user demand information data, and establishing a three-dimensional model; S2: Calculate the crankshaft deformation according to the crankshaft working parameters; S3: Calculate the oil film thickness distribution between the crankshaft (100) and the bearing (200) under all working conditions based on the three-dimensional model and the crankshaft deformation, and determine the minimum oil film thickness H min whether the thickness is not less than a preset thickness, and whether the oil film thickness uniformity coefficient H is not greater than a first preset coefficient; if so, proceed to S4; if not, return to S1 to optimize the structural dimensions of the crankshaft (100) and the bearing bush (200); S4: Calculate, based on the three-dimensional model and the crankshaft deformation, whether the oil film thickness uniformity coefficient H between the crankshaft (100) and the bearing (200) under common working conditions satisfies the requirement of being no greater than a second preset coefficient, wherein the second preset coefficient is less than the first preset coefficient. If so, the design is completed. If not, return to S1 to optimize the structural dimensions of the crankshaft (100) and the bearing (200).

2. The method for designing a crankshaft assembly according to claim 1, characterized in that: The S1 includes: S101: Acquire and analyze user application scenario information; S102: selecting a typical road spectrum and a corresponding front-end and rear-end output structure of the engine according to the user application scenario information; S103: Determine the initial structural dimensions of the crankshaft (100) and the bearing (200) according to the selected typical road spectrum and the corresponding front and rear end output structures of the engine, and establish a three-dimensional model.

3. The method for designing a crankshaft assembly according to claim 1, characterized in that: The crankshaft operating parameters in S2 include the crankshaft front and rear end loads, rotation speed, torque and engine cylinder pressure.

4. The method for designing a crankshaft assembly according to any one of claims 1 to 3, characterized in that: The calculation method of the oil film thickness uniformity coefficient H in S3 and S4 is: Among them, H max is the maximum oil film thickness, H average is the average oil film thickness between the crankshaft (100) and the bearing (200).

5. The method for designing a crankshaft assembly according to any one of claims 1 to 3, characterized in that: The preset thickness is 1 μm.

6. The method for designing a crankshaft assembly according to any one of claims 1 to 3, characterized in that: The first preset coefficient is 0.

3.

7. The method for designing a crankshaft assembly according to any one of claims 1 to 3, characterized in that: The second preset coefficient is 0.

2.

8. A crankshaft assembly, characterized in that: The crankshaft assembly is a crankshaft assembly designed using the crankshaft assembly design method as described in any one of claims 1 to 7.

9. The crankshaft assembly according to claim 8, characterized in that In the axial direction of the crankshaft (100) of the crankshaft assembly, the diameter of the middle portion of the main journal (110) of the crankshaft (100) is larger than the diameters at both ends of the main journal (110), and / or the diameter of the middle portion of the connecting rod journal of the crankshaft (100) is larger than the diameters at both ends of the connecting rod journal; In the axial direction of the crankshaft (100) of the crankshaft assembly, the wall thickness of the middle portion of the bearing shell (200) is greater than the wall thickness at both ends of the bearing shell (200).

10. An engine, comprising a crankshaft assembly, characterized in that: The crankshaft assembly is the crankshaft assembly according to claim 8 or 9.

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