CN118133702A - Design method of cylinder bore of engine - Google Patents

Abstract

The invention discloses a design method for a cylinder bore of an engine, wherein the cylinder bore comprises a cylindrical surface and a conical surface connected in sequence, and a plurality of microgrooves are arranged on the inner surface of the top dead center region of the cylindrical surface; the design method comprises: performing simulation experiments by using fluid dynamics simulation software and performing experiments on the engine on an engine bench to obtain a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy; according to the dynamic model, obtaining a plurality of groups of first data characterizing the corresponding relationship between the structures of different microgrooves and the peak values of the friction work and the knocking kinetic energy, and obtaining a plurality of groups of second data characterizing the corresponding relationship between the profile parameters of different cylindrical surfaces and conical surfaces and the peak values of the friction work and the knocking kinetic energy; and obtaining the structures of the microgrooves, the profile parameters of the cylindrical surface and the conical surface corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in the plurality of groups of first data and the plurality of groups of second data.

Description

Design method of cylinder bore of engine

Technical Field

At least one embodiment of the present invention relates to the technical field of engine design, and in particular to a method for designing a cylinder bore of an engine.

Background technique

As the degree of diesel engine combustion intensification increases, the thermal load and mechanical load on the cylinder bore during the operation of the diesel engine increase, and the deformation of the cylinder bore of the engine under the action of thermal load and mechanical load is also prone to increase. Studies have shown that the increase in the irregular deformation of the cylinder liner will lead to an increase in the friction loss between the piston ring and the piston and the inner wall of the cylinder bore. The friction loss generated during the operation of the piston accounts for 50% to 68% of the total friction loss of the engine. For every 10% increase in engine friction loss, fuel consumption increases by 3% to 5%, and the power performance will also decrease accordingly. In addition, the irregular deformation of the cylinder bore will lead to an increase in the cylinder clearance, thereby causing an increase in the piston knocking noise. Therefore, reducing the friction work of the two pairs of friction pairs between the piston and the inner wall of the cylinder bore and the piston ring and the inner wall of the cylinder bore, as well as the peak value of the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore, is of great significance to improving the economy of the diesel engine and reducing noise pollution.

In the prior art, one of the three methods, namely optimizing the piston skirt profile, setting tiny pits on the inner wall of the cylinder bore, and optimizing the cylinder bore profile, is mainly used to reduce the friction loss between the piston and the piston ring and the inner wall of the cylinder bore, as well as the knocking kinetic energy of the piston hitting the inner wall of the cylinder bore. However, the method of optimizing the piston skirt profile can only reduce the friction loss on the friction pair between the piston and the inner wall of the cylinder bore, and does not improve the friction loss on the friction pair between the piston ring and the inner wall of the cylinder bore. Furthermore, the method of optimizing the cylinder bore profile improves the friction loss between the two pairs of friction pairs, namely the piston and the inner wall of the cylinder bore and the piston ring and the inner wall of the cylinder bore to a certain extent, but ignores the fact that the gap between the two pairs of friction pairs, namely the piston ring and the inner wall of the cylinder bore and the piston and the inner wall of the cylinder bore, is too large, which leads to an increase in the knocking noise of the piston hitting the cylinder bore, which is a negative impact. Furthermore, by providing tiny pits on the inner wall of the cylinder bore, the friction loss between the two pairs of friction pairs, namely the piston and the inner wall of the cylinder bore and the piston ring and the inner wall of the cylinder bore, is improved. Although the gap between the two pairs of friction pairs, namely the piston ring and the inner wall of the cylinder bore and the piston and the inner wall of the cylinder bore, is not increased, it does not improve the knocking kinetic energy generated by the piston hitting the inner wall of the cylinder bore.

Therefore, the existing method of designing the cylinder bore of an engine by only setting tiny pits on the inner wall of the cylinder bore has the problem of being unable to simultaneously reduce the friction loss between the piston and the piston ring and the inner wall of the cylinder bore, as well as the knocking kinetic energy generated by the piston hitting the inner wall of the cylinder bore.

Summary of the invention

In view of this, the present invention provides a design method for a cylinder bore of an engine to reduce the friction loss between the piston and the piston ring and the inner wall of the cylinder bore, and to reduce the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore.

According to an embodiment of the present invention, a design method for a cylinder bore of an engine is provided, wherein the engine comprises a piston, a piston ring and a cylinder, wherein the bore of the cylinder comprises a cylindrical surface and a conical surface connected in sequence along a vertical direction, wherein the inner surface of the top dead center region of the cylindrical surface is provided with a plurality of microgrooves, wherein during operation of the engine, the piston and the piston ring respectively rub against the inner wall of the cylinder bore to generate friction work, and the piston strikes the cylinder to generate striking kinetic energy; the design method comprises: performing simulation experiments using fluid dynamics simulation software and conducting experiments on the engine on an engine bench to obtain a shape characterizing the cylinder bore A dynamic model for the correspondence between parameters and the friction work and the knocking kinetic energy; based on the dynamic model, multiple groups of first data are obtained for characterizing the correspondence between the structures of different microgrooves and the peak values of the friction work and the knocking kinetic energy, and multiple groups of second data are obtained for characterizing the correspondence between the profile parameters of different cylindrical surfaces and conical surfaces and the peak values of the friction work and the knocking kinetic energy; and the structures of the microgrooves, the profile parameters of the cylindrical surfaces and the conical surfaces corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in the multiple groups of the first data and the multiple groups of the second data are obtained.

According to an embodiment of the present invention, the design method also includes: based on orthogonal experiments, obtaining the influence weights of the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface on the friction work and the peak value of the impact kinetic energy, and according to the influence weights, based on the dynamic model, obtaining the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface corresponding to the minimum value of the friction work and the minimum value of the peak value of the impact kinetic energy in multiple groups of the first data and multiple groups of the second data.

According to an embodiment of the present invention, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained by performing simulation experiments using fluid dynamics simulation software and performing experiments on the engine on an engine bench, including: performing simulation experiments using fluid dynamics simulation software to obtain the first friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder respectively corresponding to different shape parameters of the cylinder bore, and the first knocking kinetic energy of the piston knocking the cylinder, to form a first dynamic model; performing experiments on the engine on an engine bench to obtain the second friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder respectively corresponding to different shape parameters of the cylinder bore, and the second knocking kinetic energy of the piston knocking the cylinder; and adjusting the first dynamic model according to the difference between the first friction work and the second friction work and the difference between the first knocking kinetic energy and the second knocking kinetic energy to obtain a calibrated second dynamic model.

According to an embodiment of the present invention, the second dynamic model includes the third friction work and the third knocking kinetic energy obtained by calibrating the first friction work and the first knocking kinetic energy, the absolute value of the difference between the third friction work and the second friction work is 5% of the second friction work, and the absolute value of the difference between the third knocking kinetic energy and the second knocking kinetic energy is 5% of the second knocking kinetic energy.

According to an embodiment of the present invention, by using fluid dynamics simulation software to conduct simulation experiments, the first friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different shape parameters of the cylinder bore, and the first knocking kinetic energy of the piston knocking the cylinder are obtained to form a first dynamic model, including: based on the fluid dynamics simulation software, a three-dimensional model including the piston, the piston ring and the cylinder bore of the cylinder is established; the three-dimensional model is meshed by finite elements to form a finite element model; thermal loads and mechanical loads are loaded on the finite element model; the deformation of the cylinder bore of the cylinder under the action of the thermal load and the mechanical load is obtained; and the first dynamic model is obtained according to the shape parameters of the cylinder bore of the cylinder and the deformation of the cylinder bore of the cylinder.

According to an embodiment of the present invention, the mechanical load includes at least one of the bolt preload between the cylinder head and the cylinder of the engine, the explosion pressure in the cylinder, and the side impact force on the cylinder hole caused by the reciprocating motion of the piston; and/or, the thermal load is at least one of the gas temperature and the convection heat transfer coefficient.

According to an embodiment of the present invention, the microgroove is a roughly circular pit; according to the second kinetic model, the single variable method is adopted to obtain the diameter of the pit, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region, and the depth of the pit, and the correspondence with the third friction work and the peak value of the third knocking kinetic energy; wherein, the diameter range of the pit is 150-250μm, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region is in the range of 20%-40%, and the depth range of the pit is 0.1-0.9mm.

According to an embodiment of the present invention, the cross-section of the cylindrical surface and the cross-section of the conical surface are both ellipses; according to the second dynamic model, the single variable method is adopted to obtain the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, and the corresponding relationship with the peak value of the third friction work and the third impact kinetic energy; wherein, the taper A of the conical surface is in the range of 0μm<A≤100μm, the height B of the cylindrical surface is in the range of 0mm<B≤100mm, and the ellipticity C of the cross-section of the cylindrical surface is in the range of 0μm<C≤150μm.

According to an embodiment of the present invention, the microgroove is a roughly circular pit, and the cross-section of the cylindrical surface and the cross-section of the conical surface are both elliptical; based on the orthogonal experiment, the influence weights of the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface on the peak values of the friction work and the knocking kinetic energy are obtained, including: based on the orthogonal experiment, an orthogonal table of the influencing factor levels including the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pit to the area of the top dead center region, the depth of the pit, the peak values of the friction work and the knocking kinetic energy are obtained; according to the orthogonal table, the influencing factors of different The first range of the levels of influencing factors on the peak values of multiple groups of friction work and knocking kinetic energy corresponding to the taper of the conical surface, different heights of the cylindrical surface, different ellipticities of the cross-section of the cylindrical surface, different diameters of the pits, different ratios of the sum of the areas of multiple pits to the area of the top dead center area, and different depths of the pits; and comparing the sizes of multiple first ranges to obtain the influence weights of the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, the diameter of the pits, the ratio of the sum of the areas of the pits to the area of the top dead center area, and the depth of the pits on the peak values of the friction work and the knocking kinetic energy.

According to an embodiment of the present invention, based on orthogonal experiments, the influence weights of the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface on the peak values of the friction work and the knocking kinetic energy are obtained, and it also includes: according to the orthogonal table, the second range of the influencing factor level of the peak value of the friction work and the knocking kinetic energy corresponding to the combination of any two of the different tapers of the conical surface, the different heights of the cylindrical surface, the different ellipticities of the cross-section of the cylindrical surface, the different diameters of the pits, the ratio of the sum of the areas of the multiple pits to the area of the upper dead center area, and the different depths of the pits are obtained; and the sizes of multiple second ranges are compared to obtain the degree of correlation between any two of the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pit to the area of the upper dead center area, and the depth of the pit in terms of the influence on the peak values of the friction work and the knocking kinetic energy.

According to the design method of the cylinder bore of the engine of the above embodiment of the present invention, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained by using fluid dynamics simulation software to conduct simulation experiments and conducting experiments on the engine on an engine bench, and the structure of the micro grooves corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy and the profile parameters of the cylindrical surface and the conical surface of the cylinder bore of the cylinder are obtained according to the dynamic model. In this way, the structure of the cylinder bore of the cylinder of the engine is optimized, while taking into account the reduction of the friction loss between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder respectively, and the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore of the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

1 is a cross-sectional view of a cylinder bore of an engine according to an embodiment of the present invention;

2 is a top view of a cylinder bore of an engine according to an embodiment of the present invention;

3 is a cross-sectional view of a microgroove on the inner wall of a cylinder bore of an engine according to an embodiment of the present invention along the axial direction of the cylinder bore;

4 is a cross-sectional view of a microgroove on the inner wall of a cylinder bore of an engine according to an embodiment of the present invention along the radial direction of the cylinder bore;

5 is a flow chart of a method for designing a cylinder bore of an engine according to an embodiment of the present invention; and

FIG. 6 is a schematic diagram of an orthogonal table of an orthogonal experiment for a method of designing a cylinder bore of an engine according to an embodiment of the present invention.

In the figure:

1-cylinder bore;

11-cylindrical surface; 111-top dead center area; 112-micro groove;

12-conical surface.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

According to the inventive concept of one aspect of the present invention, a design method for a cylinder bore of an engine is provided, wherein the engine comprises a piston, a piston ring and a cylinder, the cylinder bore of the cylinder comprises a cylindrical surface and a conical surface connected in sequence along a vertical direction, and the inner surface of the top dead center area of the cylindrical surface is provided with a plurality of microgrooves, wherein during the operation of the engine, the piston and the piston ring respectively rub against the inner wall of the cylinder bore to generate friction work, and the piston knocks the cylinder to generate knocking kinetic energy; the design method comprises: obtaining a dynamic model characterizing the correspondence between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy by performing simulation experiments using fluid dynamics simulation software and performing experiments on the engine on an engine bench; obtaining, according to the dynamic model, a plurality of groups of first data characterizing the correspondence between the structures of different microgrooves and the peak values of the friction work and the knocking kinetic energy, and obtaining a plurality of groups of second data characterizing the correspondence between the profile parameters of different cylindrical surfaces and conical surfaces and the peak values of the friction work and the knocking kinetic energy; and obtaining the structures of the microgrooves, the profile parameters of the cylindrical surfaces and the conical surfaces corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in the plurality of groups of first data and the plurality of groups of second data.

Fig. 1 is a cross-sectional view of a cylinder bore of an engine of an embodiment of the present invention; Fig. 2 is a top view of a cylinder bore of an engine of an embodiment of the present invention; Fig. 3 is a cross-sectional view of a microgroove on the inner wall of a cylinder bore of an engine of an embodiment of the present invention along the axial direction of the cylinder bore; Fig. 4 is a cross-sectional view of a microgroove on the inner wall of a cylinder bore of an engine of an embodiment of the present invention along the radial direction of the cylinder bore; and Fig. 5 is a flow chart of a design method of a cylinder bore of an engine of an embodiment of the present invention.

According to an exemplary embodiment of the present invention, please refer to Figures 1-5, a design method for a cylinder bore of an engine is provided. The engine includes a piston, a piston ring and a cylinder. The cylinder bore 1 of the cylinder includes a cylindrical surface 11 and a conical surface 12 connected in sequence along the vertical direction, and the inner surface of the top dead center area 111 of the cylindrical surface 11 is provided with a plurality of micro grooves 112. Wherein, during the operation of the engine, the piston and the piston ring respectively rub against the inner wall of the cylinder bore 1 to generate friction work, and the piston knocks the cylinder to generate knocking kinetic energy. The design method includes: by using fluid dynamics simulation software to perform simulation experiments and conducting experiments on the engine on an engine bench, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained. According to the dynamic model, a plurality of first data sets are obtained for characterizing the corresponding relationship between the structure of different micro grooves and the peak values of the friction work and the knocking kinetic energy, and a plurality of second data sets are obtained for characterizing the corresponding relationship between the profile parameters of different cylindrical surfaces and conical surfaces and the peak values of the friction work and the knocking kinetic energy. The micro-groove structure, cylindrical surface and conical surface profile parameters corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in the multiple sets of first data and the multiple sets of second data are obtained.

In this embodiment, by using fluid dynamics simulation software to conduct simulation experiments and conducting experiments on the engine on an engine bench, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained, and the structure of the micro groove corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy, as well as the profile parameters of the cylindrical surface and the conical surface of the cylinder bore of the cylinder are obtained according to the dynamic model. The structure of the cylinder bore of the cylinder of the engine is optimized, so as to adjust the gap between the moving surface of the piston ring and the inner wall of the cylinder bore of the cylinder, and the gap between the piston and the inner wall of the cylinder bore of the cylinder, respectively, improve the oil film distribution between the two pairs of friction pairs of the piston and the inner wall of the cylinder bore of the cylinder, and the piston ring and the inner wall of the bore of the cylinder, which can reduce the friction loss between the piston and the inner wall of the cylinder bore of the cylinder, and can reduce the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore of the cylinder.

It should be noted that, in this embodiment, the profile parameters of the cylindrical surface and the conical surface refer to the outer geometric parameters of the cylindrical surface and the conical surface.

In some exemplary embodiments, referring to Figure 5, the design method also includes: based on orthogonal experiments, obtaining the influence weights of the micro-groove structure, cylindrical surface and conical surface profile parameters on the peak values of friction work and impact kinetic energy, and according to the influence weights, based on the dynamic model, obtaining the micro-groove structure, cylindrical surface and conical surface profile parameters corresponding to the minimum value of the friction work and the minimum value of the peak value of the impact kinetic energy in multiple groups of first data and multiple groups of second data.

In some exemplary embodiments, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained by performing simulation experiments using fluid dynamics simulation software and performing experiments on the engine on an engine bench, including: performing simulation experiments using fluid dynamics simulation software to obtain the first friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different shape parameters of the cylinder bore, and the first knocking kinetic energy of the piston knocking the cylinder, to form a first dynamic model. Performing experiments on the engine on an engine bench to obtain the second friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different shape parameters of the cylinder bore, and the second knocking kinetic energy of the piston knocking the cylinder. According to the difference between the first friction work and the second friction work and the difference between the first knocking kinetic energy and the second knocking kinetic energy, the first dynamic model is adjusted to obtain a calibrated second dynamic model.

It should be noted that, in the present embodiment, an engine is tested on an engine test bench, and the second friction work of two pairs of friction pairs, namely, the piston and the inner wall of the cylinder bore, and the piston ring and the inner wall of the cylinder bore, as well as the knocking noise of the piston hitting the inner wall of the cylinder bore, are measured to obtain the second friction work of two pairs of friction pairs, namely, the inner wall of the cylinder bore of the piston and the inner wall of the cylinder bore, and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different shape parameters of the cylinder bore, as well as the second knocking kinetic energy of the piston hitting the inner wall of the cylinder bore of the cylinder.

In some exemplary embodiments, the second dynamic model includes the third friction work and the third striking kinetic energy obtained by calibrating the first friction work and the first striking kinetic energy, the absolute value of the difference between the third friction work and the second friction work is 5% of the second friction work, and the absolute value of the difference between the third striking kinetic energy and the second striking kinetic energy is 5% of the second striking kinetic energy.

In some exemplary embodiments, by using fluid dynamics simulation software to conduct simulation experiments, the first friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different cylinder bore shape parameters, and the first knocking kinetic energy of the piston knocking the cylinder are obtained to form a first dynamic model, including: based on the fluid dynamics simulation software, a three-dimensional model including the piston, the piston ring and the cylinder bore of the cylinder is established. Finite element meshing is performed on the three-dimensional model to form a finite element model. Thermal loads and mechanical loads are applied to the finite element model. The deformation of the cylinder bore of the cylinder under the action of thermal loads and mechanical loads is obtained. According to the shape parameters of the cylinder bore of the cylinder and the deformation of the cylinder bore of the cylinder, the first dynamic model is obtained.

It should be noted that, in this embodiment, in the process of establishing the first dynamic model by conducting simulation experiments using fluid dynamics simulation software, the chamfers and roundings below 2 mm in the piston-piston ring-cylinder bore three-dimensional solid model are deleted to improve the calculation efficiency without affecting the technical effect.

Furthermore, in the process of finite element meshing of the three-dimensional model, the mesh layout of the inner wall of the cylinder bore of the cylinder is encrypted, and the mesh type is a tetrahedral mesh.

In some exemplary embodiments, the mechanical load includes at least one of the bolt pre-tightening force between the cylinder head and the cylinder of the engine, the explosion pressure in the cylinder, and the side impact force caused by the reciprocating motion of the piston on the cylinder bore. The thermal load is at least one of the gas temperature and the convection heat transfer coefficient.

In some exemplary embodiments, referring to FIG. 3-FIG. 4, the microgrooves are substantially circular pits. According to the second kinetic model, a single variable method is used to obtain the corresponding relationships between the diameter of the pit, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region, and the depth of the pit and the peak values of the third friction work and the third knocking kinetic energy. Among them, the diameter d of the pit ranges from 150 to 250 μm, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region ranges from 20% to 40%, and the depth h of the pit ranges from 0.1 to 0.9 mm.

It should be noted that, referring to Figures 3 and 4, in this embodiment, the microgrooves are roughly circular pits, the diameter d of the pits ranges from 150 to 250 μm, the depth h of the pits ranges from 0.1 to 0.9 mm, and the ratio of the sum of the areas of the multiple pits to the area of the top dead center region ranges from 20% to 40%.

In some exemplary embodiments, referring to FIG. 1-FIG. 2, the cross-section of the cylindrical surface and the cross-section of the conical surface are both elliptical. According to the second dynamic model, the single variable method is used to obtain the corresponding relationship between the taper of the conical surface, the height of the cylindrical surface, and the ellipticity of the cross-section of the cylindrical surface and the peak values of the third friction work and the third knocking kinetic energy. Among them, the taper A of the conical surface ranges from 0μm<A≤100μm, the height B of the cylindrical surface ranges from 0mm<B≤100mm, and the ellipticity C of the cross-section of the cylindrical surface ranges from 0μm<C≤150μm.

It should be noted that, in this embodiment, referring to Figures 1 and 2, the cross section of the cylindrical surface is an ellipse, the minor axis diameter of the ellipse is L, and the ellipticity C of the cross section of the cylindrical surface is in the range of 0μm<C≤150μm. In other words, the major axis diameter of the cross section of the cylindrical surface is L+2C. The taper A of the conical surface is in the range of 0μm<A≤100μm, that is, the minor axis diameter of the maximum cross section of the conical surface is L+2A. The height B of the cylindrical surface is in the range of 0mm<B≤100mm, in other words, the distance between the top of the conical surface and the top of the cylinder bore of the cylinder is B.

In some exemplary embodiments, the microgrooves are roughly circular pits, and the cross-sections of the cylindrical surface and the conical surface are both elliptical. Based on orthogonal experiments, the influence weights of the microgrooves structure, the cylindrical surface, and the profile parameters of the conical surface on the peak values of the friction work and the knocking kinetic energy are obtained, including: based on the orthogonal experiment, an orthogonal table of the influence factor levels of the peak values of the friction work and the knocking kinetic energy is obtained, including the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pits to the area of the top dead center region, the depth of the pit, and the peak values of the friction work and the knocking kinetic energy. According to the orthogonal table, the first range of the influence factor levels of multiple groups of the peak values of the friction work and the knocking kinetic energy corresponding to different tapers of the conical surface, different heights of the cylindrical surface, different ellipticities of the cross-sections of the cylindrical surface, different diameters of the pits, different ratios of the sum of the areas of multiple pits to the area of the top dead center region, and different depths of the pits are obtained. By comparing the sizes of multiple first extreme differences, we can obtain the influence weights of the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pits to the area of the top dead center, and the depth of the pit on the friction work and the peak value of the impact kinetic energy.

In some exemplary embodiments, based on orthogonal experiments, the influence weights of the microgroove structure, the cylindrical surface and the conical surface profile parameters on the peak values of the friction work and the knocking kinetic energy are obtained, and the second range of the influence factor level of the peak values of the friction work and the knocking kinetic energy corresponding to the combination of any two of the different conical surface tapers, different cylindrical surface heights, different cylindrical surface cross-sectional ellipticities, different pit diameters, different ratios of the sum of the areas of multiple pits to the area of the top dead center area, and different pit depths is obtained according to the orthogonal table. Compare the sizes of multiple second ranges to obtain the degree of correlation between any two of the conical surface taper, the cylindrical surface height, the ellipticity of the cylindrical surface cross-sectional area, the pit diameter, the ratio of the sum of the areas of the pit to the area of the top dead center area, and the pit depth in terms of the influence on the peak values of the friction work and the knocking kinetic energy.

FIG. 6 is a schematic diagram of an orthogonal table of an orthogonal experiment for a method of designing a cylinder bore of an engine according to an embodiment of the present invention.

It should be noted that, in this embodiment, referring to FIG. 6 , the orthogonal experimental design is an orthogonal design table of L27-3-13, and an orthogonal calculation of six factors and three levels is performed.

The six factors are the diameter of the pit, the depth of the pit, the ratio of the sum of the areas of multiple pits to the area of the top dead center, the taper of the conical surface, the height of the cylindrical surface, and the ellipticity of the cross section of the cylindrical surface. Three levels are set for each factor with three influencing factor level values.

In detail, as shown in FIG6 , column numbers 1-13 respectively represent factors affecting the friction work of the two pairs of friction pairs between the piston and the inner wall of the cylinder bore of the cylinder, and between the piston ring and the inner wall of the cylinder bore of the cylinder, and the peak value of the knocking kinetic energy generated by the piston knocking the cylinder, such as the diameter of the pit, the depth of the pit, the ratio of the sum of the areas of multiple pits to the area of the top dead center area, the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, the combination of the diameter of the pit and the depth of the pit, the combination of the taper of the conical surface and the ellipticity of the cross section of the cylindrical surface, etc. Test numbers 1-27 respectively represent 27 groups of tests under any variable factor in column numbers 1-13, and obtain 27 groups of influencing factor levels corresponding to any variable factor in column numbers 1-13. Among them, there are 9 groups of test results with influencing factor level values of 1, 2, and 3 in the 27 groups of influencing factor levels.

The calculation method of the range in the orthogonal experiment in this embodiment is described as follows:

Taking the variable factor with column number 1 as an example, setting column number 1 as the variable factor of the pit diameter, it can be seen from the orthogonal table that the influence factor level value of the 9 groups of tests with test numbers 1-9 is 1, and the input values of the pit diameters corresponding to these 9 groups of tests are summed up to be R1; the influence factor level value of the 9 groups of tests with test numbers 10-18 is 2, and the input values of the pit diameters corresponding to these 9 groups of tests are summed up to be R2; the influence factor level value of the 9 groups of tests with test numbers 19-27 is 3, and the input values of the pit diameters corresponding to these 9 groups of tests are summed up to be R3. The maximum and minimum values of R1, R2, and R3 are subtracted to obtain the first range of the influence factor level of the peak values of the friction work and the knocking kinetic energy corresponding to the pit diameter. By analogy, the first extreme difference of the levels of influencing factors on the peak values of friction work and impact kinetic energy corresponding to the depth of the pit, the ratio of the sum of the areas of multiple pits to the area of the top dead center, the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross-section of the cylindrical surface, etc. can be obtained by the above method.

Furthermore, setting column number 7 as the variable factor of the combination of the diameter and the depth of the pit, it can be seen from the orthogonal table that the level value of the influencing factor of the 9 groups of experiments with test numbers of 1, 4, 7, 11, 14, 17, 21, 24, and 27 is 1, and the input values of the diameter and the depth of the pit corresponding to these 9 groups of experiments are summed up to calculate R4; the level value of the influencing factor of the 9 groups of experiments with test numbers of 2, 5, 8, 12, 15, 18, 19, 22, and 25 is 2, and the input values of the diameter and the depth of the pit corresponding to these 9 groups of experiments are summed up to calculate R5; the level value of the influencing factor of the 9 groups of experiments with test numbers of 3, 6, 9, 10, 13, 16, 20, 23, and 26 is 3, and the input values of the diameter and the depth of the pit corresponding to these 9 groups of experiments are summed up to calculate R6. The maximum and minimum values of R4, R5, and R6 are subtracted to obtain the second range of the influencing factor level of the peak value of the friction work and the knocking kinetic energy corresponding to the combination of the diameter of the pit and the depth of the pit. Similarly, the second range of the influencing factor level of the peak value of the friction work and the knocking kinetic energy corresponding to the combination of any two of the different tapers of the conical surface, the different heights of the cylindrical surface, the different ellipticities of the cross-section of the cylindrical surface, the different diameters of the pits, the different ratios of the sum of the areas of the plurality of pits to the area of the top dead center region, and the different depths of the pits.

Among them, the larger the first range, the greater the influence of the factor on the friction work of the two friction pairs of the piston and the inner wall of the cylinder bore of the cylinder, and the piston ring and the inner wall of the cylinder bore of the cylinder; conversely, it means that the influence of the factor on the friction work of the two friction pairs of the piston and the inner wall of the cylinder bore of the cylinder, and the piston ring and the inner wall of the cylinder bore of the cylinder is smaller. Furthermore, the larger the second range, the stronger the interaction between the two factors; conversely, it means that the interaction between the two factors is weaker.

Furthermore, in the present embodiment, in the process of obtaining the micro-groove structure, cylindrical surface and conical surface profile parameters corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in multiple sets of first data and multiple sets of second data, in addition to considering the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy, the piston leakage also needs to be considered to determine the optimal parameters of the micro-groove structure, cylindrical surface and conical surface profile parameters.

In addition, in the related art, there are three methods for reducing the friction work of the two friction pairs of the piston and the inner wall of the cylinder bore, and the piston ring and the inner wall of the cylinder bore, and reducing the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore:

The first method is to improve the friction, lubrication and knocking characteristics of the piston from the perspective of piston structure design. By optimizing the parameters of the skirt profile of the piston, the friction work of the friction pair between the piston and the inner wall of the cylinder bore can be effectively reduced, as well as the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore. However, this method only improves the friction loss between the piston and the cylinder bore, and it is difficult to improve the friction loss on the friction pair between the piston ring and the cylinder bore. Moreover, due to the very low degree of CNC manufacturing in the current piston manufacturing and the low processing accuracy, it is difficult to match the original design intention.

The second method is to start from the design perspective of the cylinder bore profile, adopt a non-cylindrical cylinder liner design in the cold state, and adjust the gap between the piston ring and the inner wall of the cylinder bore, and between the piston and the inner wall of the cylinder bore to adjust the distribution of the lubricating oil film, so as to reduce the friction loss. However, the current non-cylindrical cylinder liner design is mainly focused on reducing the friction work by adjusting the gap between the two pairs of friction pairs, ignoring the negative impact of the piston hitting the inner wall of the cylinder bore when the gap between the two pairs of friction pairs is too large.

The third method is to set micro grooves on the inner wall of the cylinder bore, and optimize the structural parameters of the micro grooves on the inner wall of the cylinder bore to reduce the friction loss between the two pairs of friction pairs, namely the piston and the inner wall of the cylinder bore, and the piston ring and the inner wall of the cylinder bore. However, there are certain limitations on improving the knocking kinetic energy generated by the piston knocking on the inner wall of the cylinder bore.

The design method of the cylinder bore of the engine of the present embodiment optimizes the shape parameters of the cylinder bore and the structure of the microgrooves arranged on the inner wall of the cylinder bore of the cylinder to obtain a cylinder bore design method combining macro and micro. In other words, macroscopically, the cylinder bore of the cylinder includes a cylindrical surface and a conical surface connected in sequence along the vertical direction, and the cross section of the cylindrical surface and the cross section of the conical surface are both elliptical. Microscopically, a microgroove is arranged in the top dead center area of the inner wall of the cylinder bore of the cylinder. Based on the construction of a dynamic model and an orthogonal test, the line parameters of the cylindrical surface and the conical surface of the cylinder bore of the cylinder, and the geometric parameters of the microgroove are optimized and designed to obtain the optimal parameters of the line parameters of the cylindrical surface and the conical surface of the cylinder bore of the cylinder, and the geometric parameters of the microgroove corresponding to the minimum value of the friction work of the two pairs of friction pairs between the piston ring and the inner wall of the cylinder bore of the cylinder and the piston and the inner wall of the cylinder bore of the cylinder, and the peak minimum value of the knocking kinetic energy generated by the piston knocking the cylinder.

Furthermore, the design method of the cylinder bore of the engine of this embodiment effectively reduces the friction work of the two friction pairs of the piston ring and the inner wall of the cylinder bore of the cylinder, and the piston and the inner wall of the cylinder bore of the cylinder, and effectively reduces the peak value of the knocking kinetic energy generated by the piston knocking on the cylinder. It overcomes the technical defects in the prior art that only the cylinder bore of a non-cylindrical cylinder or only microgrooves are set on the inner wall of the cylinder bore of the cylinder, resulting in the peak value of the knocking kinetic energy generated by the piston knocking on the cylinder is too high and difficult to improve.

The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method for designing a cylinder bore of an engine, the engine comprising a piston, a piston ring and a cylinder, the cylinder bore (1) of the cylinder comprising a cylindrical surface (11) and a conical surface (12) connected in sequence along a vertical direction, the inner surface of the top dead center region (111) of the cylindrical surface (11) being provided with a plurality of micro grooves (112), wherein during operation of the engine, the piston and the piston ring respectively rub against the inner wall of the cylinder bore (1) to generate friction work, and the piston knocks against the cylinder to generate knocking kinetic energy; The design method comprises: By using fluid dynamics simulation software to conduct simulation experiments and conducting experiments on the engine on an engine bench, a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder hole and the friction work and the knocking kinetic energy is obtained; According to the dynamic model, a plurality of first data sets are obtained for characterizing the corresponding relationship between the structures of different microgrooves and the peak values of the friction work and the knocking kinetic energy, and a plurality of second data sets are obtained for characterizing the corresponding relationship between the profile parameters of different cylindrical surfaces and conical surfaces and the peak values of the friction work and the knocking kinetic energy; and The microgroove structure, the cylindrical surface and the conical surface profile parameters corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in multiple sets of the first data and multiple sets of the second data are obtained. 2. The method for designing a cylinder bore of an engine according to claim 1, further comprising: Based on orthogonal experiments, the influence weights of the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface on the friction work and the peak value of the knocking kinetic energy are obtained, and according to the influence weights and based on the dynamic model, the structure of the microgroove, the profile parameters of the cylindrical surface and the conical surface corresponding to the minimum value of the friction work and the minimum value of the peak value of the knocking kinetic energy in multiple groups of the first data and multiple groups of the second data are obtained. 3. The method for designing a cylinder bore of an engine according to claim 1, wherein a dynamic model characterizing the corresponding relationship between the shape parameters of the cylinder bore and the friction work and the knocking kinetic energy is obtained by performing simulation experiments using fluid dynamics simulation software and performing experiments on the engine on an engine bench, comprising: By using fluid dynamics simulation software to conduct simulation experiments, the first friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder, and the first knocking kinetic energy of the piston knocking the cylinder corresponding to different shape parameters of the cylinder bore are obtained to form a first dynamic model; By conducting an experiment on the engine on an engine bench, the second friction work generated by the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder, respectively, and the second knocking kinetic energy of the piston knocking the cylinder, corresponding to different shape parameters of the cylinder bore, are obtained; and According to the difference between the first friction work and the second friction work and the difference between the first striking kinetic energy and the second striking kinetic energy, the first dynamic model is adjusted to obtain a calibrated second dynamic model. 4. The design method of the cylinder bore of an engine according to claim 3, wherein the second dynamic model includes a third friction work and a third knocking kinetic energy obtained by calibrating the first friction work and the first knocking kinetic energy, the absolute value of the difference between the third friction work and the second friction work is 5% of the second friction work, and the absolute value of the difference between the third knocking kinetic energy and the second knocking kinetic energy is 5% of the second knocking kinetic energy. 5. The method for designing a cylinder bore of an engine according to claim 3, wherein a first friction work representing the friction between the piston and the piston ring and the inner wall of the cylinder bore of the cylinder corresponding to different shape parameters of the cylinder bore, and a first knocking kinetic energy of the piston knocking the cylinder are obtained by performing simulation experiments using fluid dynamics simulation software to form a first dynamic model, including: Based on fluid dynamics simulation software, a three-dimensional model including the piston, the piston ring and the cylinder bore of the cylinder is established; Performing finite element meshing on the three-dimensional model to form a finite element model; Applying thermal load and mechanical load to the finite element model; Obtaining a deformation amount of a cylinder bore of the cylinder under the action of the thermal load and the mechanical load; and The first dynamic model is obtained according to the shape parameters of the cylinder bore of the cylinder and the deformation amount of the cylinder bore of the cylinder. 6. The method for designing a cylinder bore of an engine according to claim 5, wherein the mechanical load comprises at least one of a bolt preload between a cylinder head and a cylinder of the engine, an explosion pressure in the cylinder, and a side impact force on the cylinder bore caused by the reciprocating motion of the piston; and/or, The heat load is at least one of the gas temperature and the convection heat transfer coefficient. 7. The method for designing a cylinder bore of an engine according to claim 4, wherein the microgrooves are substantially circular pits; According to the second dynamic model, using a single variable method, the corresponding relationships between the diameter of the pit, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region, the depth of the pit, and the third friction work and the peak value of the third knocking kinetic energy are obtained respectively; The diameter of the pits is in the range of 150-250 μm, the ratio of the sum of the areas of the plurality of pits to the area of the top dead center region is in the range of 20%-40%, and the depth of the pits is in the range of 0.1-0.9 mm. 8. The method for designing a cylinder bore of an engine according to claim 4, wherein the cross section of the cylindrical surface and the cross section of the conical surface are both elliptical; According to the second dynamic model, using a single variable method, the corresponding relationships between the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, and the peak values of the third friction work and the third striking kinetic energy are obtained respectively; The taper A of the conical surface is in the range of 0 μm<A≤100 μm, the height B of the cylindrical surface is in the range of 0 mm<B≤100 mm, and the ellipticity C of the cross section of the cylindrical surface is in the range of 0 μm<C≤150 μm. 9. The method for designing a cylinder bore of an engine according to claim 2, wherein the microgrooves are substantially circular pits, and the cross-sections of the cylindrical surface and the conical surface are both elliptical; Based on the orthogonal experiment, the influence weights of the structure of the micro-groove, the profile parameters of the cylindrical surface and the conical surface on the peak values of the friction work and the knocking kinetic energy are obtained, including: Based on the orthogonal experiment, an orthogonal table of influencing factors including the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pits to the area of the top dead center region, the depth of the pit, the friction work and the peak value of the knocking kinetic energy is obtained; Obtaining, according to the orthogonal table, first ranges of influencing factor levels of multiple groups of peak values of friction work and knocking kinetic energy corresponding to different tapers of the conical surface, different heights of the cylindrical surface, different ellipticities of the cross-section of the cylindrical surface, different diameters of the pits, different ratios of the sum of the areas of the plurality of pits to the area of the top dead center region, and different depths of the pits; and Compare the sizes of multiple first extreme differences to obtain the influence weights of the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pits to the area of the top dead center region, and the depth of the pit on the friction work and the peak value of the impact kinetic energy. 10. The method for designing a cylinder bore of an engine according to claim 9, wherein, based on orthogonal experiments, the influence weights of the structure of the micro groove, the profile parameters of the cylindrical surface and the conical surface on the peak values of the friction work and the knocking kinetic energy are obtained, and further comprising: According to the orthogonal table, a second range of the influencing factor level of the peak value of the friction work and the knocking kinetic energy corresponding to any two combinations of different tapers of the conical surface, different heights of the cylindrical surface, different ellipticities of the cross section of the cylindrical surface, different diameters of the pits, different ratios of the sum of the areas of the plurality of pits to the area of the top dead center region, and different depths of the pits is obtained; and By comparing the sizes of multiple second extreme differences, the degree of correlation between any two of the taper of the conical surface, the height of the cylindrical surface, the ellipticity of the cross section of the cylindrical surface, the diameter of the pit, the ratio of the sum of the areas of the pit to the area of the top dead center region, and the depth of the pit in terms of their influence on the friction work and the peak value of the knocking kinetic energy is obtained.