A friction analysis method for engine complete assembly

Abstract

This invention provides a method for analyzing friction in an entire engine assembly. Based on a constructed friction analysis model for the entire engine assembly, the friction work values for each component and the entire engine assembly at various speeds are analyzed, calculated, and statistically analyzed. The values are then compared with the design values in the entire engine assembly design database. Components with significant system friction are optimized for their basic parameters, and the analysis is resubmitted until the friction levels of each component and the entire engine assembly meet the design targets. Through model analysis, the method rapidly determines the overall engine friction level and the friction distribution of each subsystem, identifies systems and components with high friction contributions, and optimizes parameters for these components, guiding friction-reducing design, thereby reducing engine fuel consumption and improving product competitiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of engine complete assembly friction analysis, and in particular to a method for engine complete assembly friction analysis. Background Art

[0002] With increasingly stringent regulations on fuel consumption and emissions, new technologies are increasingly being adopted to reduce fuel consumption, particularly those that reduce mechanical losses within engine components, where friction plays a dominant role. Friction in automotive engines is unavoidable, due to its inherent structure and operating characteristics, and it is detrimental to the engine. Therefore, studying the overall engine assembly friction level and the contribution of each component can help focus on reducing factors with significant friction contributions at a lower cost. However, current research focuses on friction reduction in each component individually, without fully understanding the contribution of each component at the overall engine level. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a friction analysis method for an engine assembly that can quickly quantify the friction level of the engine assembly and the contribution of each component, thereby providing an analysis method for identifying key parameters for reducing friction.

[0004] To achieve the above object, the present invention provides a friction analysis method for an engine assembly, comprising the following steps:

[0005] Step S1. Based on the engine assembly design database, a friction analysis model of the entire engine assembly is constructed. The model components include reciprocating components, crankshaft system, balance shaft system, valve timing system, front-end accessory system, and oil lubrication system;

[0006] Step S2. Loading the basic parameters of each component into the overall engine assembly friction analysis model, including basic engine performance parameters, basic reciprocating component performance parameters, basic accessory system parameters, basic crankshaft system parameters, basic balance shaft assembly parameters, basic valve train assembly parameters, and basic oil change parameters;

[0007] Step S3. Set the engine assembly friction analysis model analysis condition list, assign the speed as a variable parameter to the corresponding condition list, set the result output type and save location, and submit the calculation;

[0008] Step S4. Import the calculated output results into an Office Excel spreadsheet to calculate the friction work values of each component and the entire engine assembly at each speed;

[0009] Step S5. Compare the statistical friction work values of each component and the complete engine assembly at each speed with the design values in the complete engine assembly design database. If the friction levels of each component and the complete engine assembly are within the design target, it means that the design parameters are qualified and the analysis ends. If the friction levels of each component and the complete engine assembly exceed the design target, find the components with the largest friction contribution in the analysis results, optimize their basic parameters, and resubmit the calculation and analysis until the friction levels of each component and the complete engine assembly meet the design target.

[0010] Specifically, the basic engine performance parameters include fuel type, layout, number of cylinders, cylinder properties and valve properties; the cylinder properties include cylinder diameter, stroke, connecting rod length and eccentricity; the valve properties include valve number and maximum lift.

[0011] Specifically, the basic parameters of the reciprocating assembly include the piston skirt length, the area of the string hole and the inner diameter, axial thickness and elastic force of the piston ring;

[0012] The piston ring elastic force calculation formula is as follows:

[0013] Radial elastic force when the piston ring is closed to the specified cylinder diameter:

[0014]

[0015] Where, F is radial elastic force, D1 is the free diameter of piston ring, D is the required cylinder diameter, E is elastic modulus, I is the moment of inertia of piston ring section, and R is the radius of the neutral layer of piston ring.

[0016] Tangential elastic force when the piston ring closes to the specified cylinder diameter:

[0017]

[0018] Among them, W is the tangential elastic force

[0019] Conversion formula between radial elastic force and tangential elastic force:

[0020]

[0021] Therefore, the piston ring friction work is calculated as follows:

[0022] W f =F×v×c f

[0023] Among them, F is the radial elastic force, v is obtained according to the mechanism movement and crankshaft speed, c f ——Calculated based on the Stribeck function curve of sliding speed, force and lubricant viscosity.

[0024] Specifically, the basic parameters of the accessory system include front-end accessory belt tension and number of pulleys, fuel pump type, engine specific power, oil pump type and layout, air-conditioning compressor, vacuum pump and generator.

[0025] Specifically, the basic parameters of the crankshaft system include the oil seal material type and diameter; bearing type, quantity, diameter and width; and balance block quantity, radius and thickness.

[0026] Specifically, the basic parameters of the balance shaft assembly include the drive form; the bearing type, quantity, diameter and width; the quantity, radius and thickness of the balance blocks.

[0027] Specifically, the basic parameters of the valve train assembly include cam mechanism layout type, drive type; drive component type; valve clearance adjustment mechanism; pulley type; oil seal material type and diameter; and bearing quantity, type, diameter, and width.

[0028] Specifically, the basic parameters of the lubricating oil include the oil density and the corresponding temperature viscosity under cold and hot states.

[0029] The beneficial effects of the present invention compared to the prior art are as follows:

[0030] 1. The engine complete assembly friction analysis method of the present invention overcomes the problem of the existing technology that is unable to quantify the friction level distribution of the engine complete assembly and each component, while considering the influence of different lubricating oil temperature viscosity of key friction pairs.

[0031] 2. The present invention provides a new technology for identifying and improving certain key parameters to improve the friction of the entire machine, which can be used for engine disassembly test evaluation and fuel consumption reduction research; and can replace some reverse drag tests and quickly respond to design change verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a flow chart of a friction analysis method for an engine complete assembly according to the present invention;

[0033] Figure 2 Schematic diagram of the friction work distribution of various components in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0035] like Figure 1 As shown, the present invention proposes a friction analysis method for an engine assembly, comprising the following steps:

[0036] Step S1. Based on the engine assembly design database, a friction analysis model of the entire engine assembly is constructed. The model components include reciprocating components, crankshaft system, balance shaft system, valve timing system, front-end accessory system, and oil lubrication system;

[0037] Step S2. Loading the basic parameters of each component into the overall engine assembly friction analysis model, including basic engine performance parameters, basic reciprocating component performance parameters, basic accessory system parameters, basic crankshaft system parameters, basic balance shaft assembly parameters, basic valve train assembly parameters, and basic oil change parameters;

[0038] The basic engine performance parameters include fuel type, layout, number of cylinders, cylinder attributes and valve attributes; the cylinder attributes include cylinder diameter, stroke, connecting rod length and eccentricity; the valve attributes include valve number and maximum lift;

[0039] The basic parameters of the reciprocating assembly include the length of the piston skirt, the area of the string hole and the inner diameter, axial thickness and elastic force of the piston ring;

[0040] The piston ring elastic force calculation formula is as follows:

[0041] Radial elastic force when the piston ring is closed to the specified cylinder diameter:

[0042]

[0043] Where, F is radial elastic force, D1 is the free diameter of piston ring, D is the required cylinder diameter, E is elastic modulus, I is the moment of inertia of piston ring section, and R is the radius of the neutral layer of piston ring.

[0044] Tangential elastic force when the piston ring closes to the specified cylinder diameter:

[0045]

[0046] Among them, W is the tangential elastic force

[0047] Conversion formula between radial elastic force and tangential elastic force:

[0048]

[0049] Therefore, the piston ring friction work is calculated as follows:

[0050] W f =F×v×c f

[0051] Among them, F is the radial elastic force, v is obtained according to the mechanism movement and crankshaft speed, c f ——Calculated based on the Stribeck function curve of sliding speed, force and lubricant viscosity.

[0052] The basic parameters of the accessory system include front-end accessory belt tension and number of pulleys, fuel pump type, engine specific power, oil pump type and layout, air conditioning compressor, vacuum pump and generator;

[0053] The basic parameters of the crankshaft system include the type and diameter of oil seal material; the type, number, diameter and width of bearings; the number, radius and thickness of balancing blocks;

[0054] The basic parameters of the balance shaft assembly include drive type; bearing type, quantity, diameter and width; balance block quantity, radius and thickness;

[0055] The basic parameters of the valve train assembly include the cam mechanism layout type, drive type; drive component type; valve clearance adjustment mechanism; pulley type; oil seal material type and diameter; bearing quantity, type, diameter and width;

[0056] The basic parameters of the lubricating oil include the oil density and the corresponding temperature viscosity under hot and cold conditions;

[0057] Step S3. Set the engine assembly friction analysis model analysis condition list, assign the speed as a variable parameter to the corresponding condition list, set the result output type and save location, and submit the calculation;

[0058] Step S4. Import the calculated output results into an Office Excel spreadsheet to calculate the friction work values of each component and the entire engine assembly at each speed;

[0059] Step S5. Compare the statistical friction work values of each component and the complete engine assembly at each speed with the design values in the complete engine assembly design database. If the friction levels of each component and the complete engine assembly are within the design target, it means that the design parameters are qualified and the analysis ends. If the friction levels of each component and the complete engine assembly exceed the design target, find the components with the largest friction contribution in the analysis results, optimize their basic parameters, and resubmit the calculation and analysis until the friction levels of each component and the complete engine assembly meet the design target.

[0060] The following uses a complete engine assembly as an example to further illustrate the optimization process of various components by the method of the present invention.

[0061] According to the above method steps, the friction analysis model of the engine assembly is constructed to obtain the friction work distribution of each component, such as Figure 2The figure shows the distribution of friction work of each component. From the perspective of the proportion of friction work of each component, the main bearing accounts for the largest proportion, followed by the piston skirt. Therefore, the optimization suggestion given is to reduce the main journal.

[0062] Table 1 below shows the changes in friction of the entire engine assembly after optimizing the main journal size parameters. As can be seen from the table, when the main journal is reduced to 65 mm, the friction work of the crankshaft system is reduced by approximately 13.3% (as a proportion of the crankshaft itself), and the friction torque is reduced by approximately 2.4% (as a proportion of the overall proportion); when the main shaft diameter is reduced to 60 mm, the friction work of the crankshaft system is reduced by approximately 25.3% (as a proportion of the crankshaft itself), and the friction torque is reduced by approximately 4.6% (as a proportion of the overall proportion). This shows that after analysis and optimization by the method of the present invention, the proportion of the main journal in the friction work of the entire engine assembly can be effectively reduced, and the friction work of the entire engine assembly can be reduced, thereby reducing engine fuel consumption and improving product competitiveness.

[0063]

[0064] In summary, the present invention's method for analyzing complete engine assembly friction overcomes existing issues, such as the inability to quantify the distribution of friction levels within the complete engine assembly and its components. It also considers the impact of varying lubricant temperature and viscosity on key friction pairs, proposes improvements for components with a significant contribution to system friction, and guides friction reduction design. Furthermore, the present invention provides a novel approach for identifying and improving certain key parameters to improve complete engine friction, which can be used for engine disassembly test evaluation and fuel consumption reduction research. It can also replace some reverse drag tests, enabling rapid response to design change verification.

[0065] The above description is only a preferred embodiment of the present invention and does not limit the structure of the present invention in any form. Any simple modification, equivalent change and modification of the above embodiment based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. A friction analysis method for an engine assembly, characterized in that: The following steps are involved: Step S1. Based on the engine assembly design database, a friction analysis model of the entire engine assembly is constructed. The model components include reciprocating components, crankshaft system, balance shaft system, valve timing system, front-end accessory system, and oil lubrication system; Step S2. Loading the basic parameters of each component into the overall engine assembly friction analysis model, including basic engine performance parameters, basic reciprocating component performance parameters, basic accessory system parameters, basic crankshaft system parameters, basic balance shaft assembly parameters, basic valve train assembly parameters, and basic lubricating oil parameters; The basic performance parameters of the reciprocating assembly include the piston skirt length, the area of the string hole and the inner diameter, axial thickness and elastic force of the piston ring; The piston ring elastic force calculation formula is as follows: Radial elastic force when the piston ring is closed to the specified cylinder diameter: ； Where, F is radial elastic force, D1 is the free diameter of piston ring, D is the required cylinder diameter, E is elastic modulus, I is the moment of inertia of piston ring section, and R is the radius of the neutral layer of piston ring. Tangential elastic force when the piston ring closes to the specified cylinder diameter: ； Where, W is the tangential elastic force; Conversion formula between radial elastic force and tangential elastic force: ； Therefore, the piston ring friction work is calculated as follows: ； Among them, F is the radial elastic force, v is obtained according to the mechanism movement and crankshaft speed, ——Calculated based on the Stribeck function curve of sliding speed, force and lubricant viscosity; Step S3. Set the engine assembly friction analysis model analysis condition list, assign the speed as a variable parameter to the corresponding condition list, set the result output type and save location, and submit the calculation; Step S4. Import the calculated output results into an Office Excel spreadsheet to calculate the friction work values of each component and the entire engine assembly at each speed; Step S5. Compare the statistical friction work values of each component and the complete engine assembly at each speed with the design values in the complete engine assembly design database. If the friction levels of each component and the complete engine assembly are within the design target, it means that the design parameters are qualified and the analysis ends. If the friction levels of each component and the complete engine assembly exceed the design target, find the components with the largest friction contribution in the analysis results, optimize their basic parameters, and resubmit the calculation and analysis until the friction levels of each component and the complete engine assembly meet the design target.

2. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic engine performance parameters include fuel type, layout, number of cylinders, cylinder properties and valve properties; the cylinder properties include cylinder diameter, stroke, connecting rod length and eccentricity; the valve properties include valve number and maximum lift.

3. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic parameters of the accessory system include front-end accessory belt tension and number of pulleys, fuel pump type, engine specific power, oil pump type and layout, air conditioning compressor, vacuum pump and generator.

4. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic parameters of the crankshaft system include the oil seal material type and diameter; bearing type, quantity, diameter and width; and balance block quantity, radius and thickness.

5. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic parameters of the balancing shaft assembly include drive type; bearing type, quantity, diameter and width; and balancing block quantity, radius and thickness.

6. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic parameters of the valve train assembly include the cam mechanism layout type, drive type; drive part type; valve gap adjustment mechanism; pulley type; oil seal material type and diameter; and bearing quantity, type, diameter and width.

7. The method for analyzing friction of an engine assembly according to claim 1, characterized in that: The basic parameters of the lubricating oil include the density of the lubricating oil and the corresponding temperature viscosity under cold and hot states.

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