A method for evaluating the deformation coordination of engine cylinder liners

Abstract

The present invention relates to a method for evaluating the coordination of engine cylinder liner deformation. According to the magnitude of each order of Fourier deformation of the cylinder liner and the overall coaxiality of the cylinder liner, the cylinder liner deformation coordination factor value is calculated to evaluate the coordination of the engine cylinder liner deformation. The closer the cylinder liner deformation coordination factor value is to 1, the better the cylinder liner deformation coordination is, and the closer it is to 0, the worse the cylinder liner deformation coordination is. The present invention conducts in-depth research on the factors affecting engine cylinder liner deformation, deformation control factors, and deformation simulation analysis and evaluation technologies, and adopts a weighted method of both cross-sectional and overall types to comprehensively evaluate cylinder liner deformation. The cross-sectional area uses the amplitudes of each order based on the Fourier method as an evaluation index; the overall type uses coaxiality as an evaluation index. At the same time, limit values are set for the amplitudes of each order of cross-sectional deformation. The cylinder liner deformation can be accurately described, and a direction for improved engine design is provided.

Description

Technical Field

[0001] The invention belongs to the technical field of engines, and in particular relates to a method for evaluating the deformation coordination of an engine cylinder liner. Background Art

[0002] Cylinder liner deformation is a direct reflection of the engine's structural rigidity. Insufficient structural rigidity and excessive deformation can lead to excessive stress in the contact area, altering the cylinder clearance, and causing adverse consequences such as friction, wear, and insufficient sealing. Cylinder liner deformation directly impacts engine combustion and performance. Inadequate deformation can lead to piston ring seal failure, deteriorating emissions, and excessive oil consumption. Therefore, cylinder liner deformation is a key engine evaluation metric.

[0003] Low-deformation cylinder liners are a key research area in current reciprocating piston internal combustion engines. Minimizing cylinder liner deformation improves piston ring sealing, reducing oil consumption and air leakage. From a design perspective, low cylinder liner deformation allows for reduced preload on the piston ring (as cylinder head bolt preload and cylinder liner deformation are mutually exclusive). This reduces frictional losses in the piston-liner system, thereby improving engine efficiency.

[0004] Depending on the cause, cylinder liner deformation can be divided into three categories: manufacturing deformation, pre-tightening deformation and operating condition deformation. Manufacturing deformation of the cylinder liner refers to the out-of-round phenomenon of the cylinder liner caused by factors such as the centering error between the cutter head and the workpiece, rotational imbalance, radial vibration of the workpiece, material strain, and residual stress generated during the machining process. The pre-tightening deformation of the cylinder liner is the deformation caused by the pre-tightening force on the pre-tightening bolt acting on the cylinder liner through the cylinder head and the engine body. The operating condition deformation of the cylinder liner refers to the deformation of the cylinder liner under the working state of the internal combustion engine, taking into account the gas pressure in the combustion chamber, the temperature field formed by the gas inside the cylinder liner and the cooling water outside the cylinder liner, the piston excitation force and other factors.

[0005] Traditional evaluation of cylinder liner deformation usually adopts a simple description of the maximum deformation, that is, the axial deformation curve of the main thrust side is used to evaluate the cylinder liner deformation through its maximum value. After that, the axial deformation information is obtained every 45°, and the main and auxiliary thrust sides, and the two curves perpendicular to them are used to describe the degree of deformation. Usually, the deformation away from the center line is positive, and the deformation close to the center line is negative. After the Fourier coefficient method of describing deformation was proposed, this method was immediately widely used. At present, the out-of-roundness evaluation method based on Fourier series is mainly used at home and abroad. It includes Fourier spectrum analysis on the cross-section of interest, such as the corresponding surface of the piston ring and the corresponding surface of the upper and lower parts of the bolt, to analyze the deformation amplitude of each order, such as Figure 1 As shown, Fourier analysis can only be performed on a specific single cross section.

[0006] The measured cylinder liner deformation is as follows Figure 2 As shown in the figure, the traditional cylinder liner deformation analysis and evaluation cannot reflect the overall deformation of the cylinder liner.

[0007] Traditional cylinder liner deformation evaluation has two main defects:

[0008] 1. The simple description and evaluation of the maximum deformation of the cylinder liner cannot reflect the overall deformation of the cylinder liner and cannot provide support for improved design.

[0009] 2. Traditional Fourier evaluation can only be applied to specific cross sections and may not necessarily find the cross section with the maximum deformation. Summary of the Invention

[0010] The present invention provides a method for evaluating the deformation coordination of an engine cylinder liner, which solves the defects of the prior art.

[0011] In order to solve the above technical problems, the present invention provides an engine cylinder liner deformation coordination evaluation method, which is characterized by: calculating a cylinder liner deformation coordination factor value based on the cylinder liner Fourier transform order deformation size and the overall coaxiality of the cylinder liner to evaluate the coordination of the engine cylinder liner deformation; the closer the cylinder liner deformation coordination factor value is to 1, the better the cylinder liner deformation coordination is, and the closer it is to 0, the worse the cylinder liner deformation coordination is;

[0012] Cylinder liner deformation coordination factor for:

[0013]

[0014] Fourier transform of the cylinder liner The order deformation amplitude, is the limit value of the deformation amplitude of this order, i.e. the maximum value, is the optimal value of the deformation amplitude of this order, i.e. the minimum value; is the cylinder liner coaxiality, is the cylinder liner coaxiality limit value, i.e. the maximum value. is the optimal value or minimum value of cylinder liner coaxiality; are the cylinder liner Fourier deformation weight and the cylinder liner overall coaxiality weight respectively;

[0015]

[0016] in, is the critical value coefficient of each order, and D is the cylinder diameter.

[0017] Furthermore, the cylinder liner coaxiality represents the maximum axial deflection of the cylinder liner and is directly calculated by the enveloping circle of the center of each cross section.

[0018] Furthermore, the critical value coefficients of each order are as follows:

[0019]

[0020] Furthermore, .

[0021] Beneficial Effects: This invention comprehensively evaluates cylinder liner deformation, conducting in-depth research on factors influencing engine cylinder liner deformation, deformation control factors, and deformation simulation analysis and evaluation techniques. It employs a weighted approach using both cross-sectional and integral methods to comprehensively assess cylinder liner deformation. The cross-sectional method uses the amplitudes of various orders based on the Fourier transform method as evaluation indicators, while the integral method uses coaxiality as an evaluation indicator. Furthermore, limit values are set for each order of cross-sectional deformation amplitude. This allows for an accurate description of cylinder liner deformation and provides guidance for improved engine design. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of deformation of Fourier coefficients of each harmonic order

[0023] Figure 2 Schematic diagram of measured cylinder liner deformation

[0024] Figure 3 Schematic diagram of the engine cylinder liner deformation coordination evaluation principle of the present invention. DETAILED DESCRIPTION

[0025] In order to make the purpose, content and advantages of the present invention more clear, the specific embodiments of the present invention are further described in detail below.

[0026] The present invention proposes a method for evaluating the coordination of engine cylinder liner deformation. The method calculates a cylinder liner deformation coordination factor value based on the deformation magnitude of each Fourier order of the cylinder liner and the overall coaxiality of the cylinder liner to evaluate the coordination of the engine cylinder liner deformation. The closer the value is to 1, the better the cylinder liner deformation coordination is, and the closer it is to 0, the worse the cylinder liner deformation coordination is.

[0027] The evaluation index of cylinder liner deformation coordination is the magnitude of the Fourier deformation of the cylinder liner holes of different cross-sections, i.e., the amplitude of each order; and the overall coaxiality of the cylinder liner. The judgment criteria are that the smaller the amplitude of each order of Fourier deformation and the coaxiality, the better, provided that they do not exceed the limit. Cylinder liner deformation coordination factor Defined as:

[0028] (1)

[0029] in, is the cylinder liner deformation coordination factor, Fourier transform of the cylinder liner The order deformation amplitude, is the limit value of the deformation amplitude of this order, i.e. the maximum value, is the optimal value or minimum value of the deformation amplitude of this order. is the cylinder liner coaxiality, which represents the maximum axial deflection of the cylinder liner and is directly calculated by the enveloping circle of the center of each section. is the cylinder liner coaxiality limit value, i.e. the maximum value. It is the optimal value or minimum value of cylinder liner coaxiality. are the weights of the above two factors, as shown in Table 2. From the above formula, we can see that the lower the maximum value of the Fourier deformation amplitude, the lower the coaxiality of the cylinder liner, the closer the deformation coordination factor is to 1, and the better the deformation coordination of the cylinder liner.

[0030] The above coordination factors need to determine the limit values of each indicator, and each indicator corresponds to a weight coefficient. The limit values of each order amplitude of the cross section under cold assembly conditions are as follows:

[0031] (2)

[0032] in, are the critical value coefficients of each order, as shown in Table 1; D is the cylinder diameter.

[0033] Table 1 Critical value coefficients of each order

[0034]

[0035] Table 2 Cylinder liner deformation evaluation weight

[0036]

[0037] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for evaluating the deformation coordination of an engine cylinder liner, characterized by: The cylinder liner deformation coordination factor is calculated based on the deformation magnitude of each order of the cylinder liner Fourier transform and the overall coaxiality of the cylinder liner to evaluate the coordination of the cylinder liner deformation of the engine. The closer the cylinder liner deformation coordination factor is to 1, the better the cylinder liner deformation coordination is, and the closer it is to 0, the worse the cylinder liner deformation coordination is. Cylinder liner deformation coordination factor for: Fourier transform of the cylinder liner The order deformation amplitude, is the limit value of the deformation amplitude of this order, i.e. the maximum value, is the optimal value of the deformation amplitude of this order, i.e. the minimum value; is the cylinder liner coaxiality, is the cylinder liner coaxiality limit value, i.e. the maximum value. is the optimal value or minimum value of cylinder liner coaxiality; are the cylinder liner Fourier deformation weight and the cylinder liner overall coaxiality weight respectively; in, is the critical value coefficient of each order, and D is the cylinder diameter.

2. The engine cylinder liner deformation coordination evaluation method according to claim 1, characterized in that: The coaxiality of the cylinder liner represents the maximum axial deflection of the cylinder liner and is directly calculated by the enveloping circle of the center of each section.

3. The engine cylinder liner deformation coordination evaluation method according to claim 1, characterized in that: The critical value coefficients of each order are as follows: 。 4. The engine cylinder liner deformation coordination evaluation method according to claim 1, characterized in that: 。

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