A method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication.

Abstract

This invention discloses a method for calculating the minimum oil supply pressure of the main oil passage to meet the requirements of bearing cooling and lubrication, belonging to the field of engine technology. It solves the problem that existing methods cannot calculate the minimum oil supply pressure for bearing cooling and lubrication. The calculation method includes establishing EHD models for connecting rod bearings and main bearings, respectively. The main bearing EHD model and the connecting rod bearing EHD model are respectively subjected to the main oil passage oil supply pressure and the connecting rod bearing pressure. The EHD calculations for the main bearings and connecting rod bearings under external characteristic conditions are then performed. Next, the EHD calculations for the connecting rod bearings under partial load at different speeds are performed. The oil supply pressure of the connecting rod bearings under test conditions is applied, and the oil temperature rise result of the connecting rod bearings under partial load is obtained. The oil supply pressure is then reduced. When the temperature rise increases to the level of the external characteristic temperature rise result at the corresponding speed, this is the recommended minimum oil supply pressure value to meet the requirements of bearing cooling and lubrication under that partial load condition. This invention's minimum oil supply pressure calculation method saves product development time and effectively improves economic efficiency.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication. Background Technology

[0002] The booming development of new energy sources has placed more stringent demands on the fuel economy of traditional engines. Frictional power loss is a significant factor affecting fuel economy, and the high-speed rotation of the crankshaft relative to the bearings generates substantial frictional losses, which account for a large proportion of the overall engine frictional power loss.

[0003] In order to reduce the frictional work of bearing bushes, in addition to changing the structural parameters of the bearing bushes themselves, such as diameter, width, and bearing clearance, reducing the oil supply pressure of the bearing bushes is also an important means of reducing frictional work. Furthermore, reducing the oil supply pressure can reduce the required flow rate of the oil pump, and a smaller oil pump can meet the cooling and lubrication requirements. The frictional losses of other components will also be reduced accordingly. At the same time, using a small-flow oil pump can also achieve cost reduction and weight reduction requirements. Currently, there is no corresponding method or process for calculating the minimum oil supply pressure to meet the cooling and lubrication requirements of bearing bushes. It can only be verified through experiments, which takes a lot of time and money. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication, which addresses the above-mentioned shortcomings of the prior art. This method saves product development cycle, reduces development costs, and effectively improves economic efficiency, and has the characteristics of high economic efficiency and strong practicality.

[0005] The technical solution adopted in this invention is: a method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication, which includes the following steps:

[0006] Step S1: Collect input data that meets the modeling requirements of main bearing EHD and connecting rod bearing EHD and main oil passage supply pressure data verified through sufficient reliability tests;

[0007] Step S2: Convert the main oil passage supply pressure into the oil supply pressure at the connecting rod bearing;

[0008] Step S3: Establish the connecting rod bearing EHD model and the main bearing EHD model respectively. The main bearing EHD model is subjected to the main oil passage supply pressure, and the connecting rod bearing EHD model is loaded with the converted connecting rod bearing supply pressure.

[0009] Step S4: Perform EHD calculations for the main bearing shell and connecting rod bearing shell under external characteristic working conditions, and obtain the oil temperature rise results and bearing lubrication results at the main bearing shell and connecting rod bearing shell.

[0010] Step S5: Evaluate whether the current temperature rise and bearing lubrication results meet the evaluation criteria;

[0011] Step S6: By comparing the oil temperature rise results of the main bearing and connecting rod bearing, it is determined that subsequent work will be carried out based on the connecting rod bearing EHD model;

[0012] Step S7: Perform EHD calculations for the connecting rod bearing under partial load at different speeds, calculate the oil supply pressure of the connecting rod bearing under the load test state, and obtain the oil temperature rise results of the connecting rod bearing under partial load.

[0013] Step S8: Reduce the oil supply pressure and perform EHD calculations for the connecting rod bearing under partial load at different speeds. When the temperature rise increases to the external characteristic temperature rise result at the corresponding speed, the reduced oil supply pressure is the recommended minimum oil supply pressure value to meet the cooling and lubrication of the main bearing and connecting rod bearing under this partial load condition.

[0014] As a further improvement, in step S1, the input data required for modeling includes engine performance parameters, engine component structural parameters, engine cylinder pressure, engine oil pressure, and engine oil temperature.

[0015] Furthermore, in step S4, the external characteristic operating condition is the 100% load operating condition of the engine operating across its entire speed range.

[0016] Furthermore, in step S6, the oil temperature rise at the connecting rod bearing will be much greater than that at the main bearing. It is necessary to determine whether the connecting rod bearing EHD model is accurate so that the data can be accurately guaranteed when the connecting rod bearing EHD model is used in the future.

[0017] Furthermore, in step S7, the load conditions can be divided into 100%, 80%, 60%, 40%, 20%, and 0% load conditions, and the minimum oil supply pressure for the corresponding working conditions is calculated.

[0018] Furthermore, in step S7, the values ​​of different speeds are taken at intervals of 20% to 30% within the engine's speed range, from the maximum value to the minimum value.

[0019] Furthermore, in step S8, the partial load temperature rise value is compared with the external characteristic temperature rise value, and the oil supply pressure is adjusted according to the difference value, with each oil supply pressure drop not exceeding 2 bar.

[0020] Beneficial effects

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) Using the main oil passage oil pressure that has completed the full reliability test as input, the EHD of the main bearing and the connecting rod bearing under external characteristic working conditions are calculated respectively. The lubrication results and temperature rise results of the main bearing and the connecting rod bearing under EHD are evaluated to determine whether the current pressure meets the requirements. The temperature rise results of the external characteristic working conditions that meet the evaluation criteria can be effectively obtained, and a reliable reference value is provided for the subsequent oil supply pressure calculation.

[0023] (2) Based on the external characteristic oil supply pressure that has passed the reliability test, the oil pressure under this working condition is not adjusted. Instead, the minimum oil supply pressure under the full working condition is determined by reducing the oil supply pressure under partial load. This serves as a reference for the selection of the oil pump. The minimum oil supply pressure can be effectively obtained through calculation. There is no need to conduct a large number of tests, which effectively saves the product development cycle, reduces development costs, and improves economic efficiency to meet the development needs of rapid product updates.

[0024] (3) The minimum oil supply pressure is confirmed by calculation so that it can be further verified by test before solidification. With the dual guarantee of test and calculation, engine failure is avoided, the development cycle is shortened, and the product can seize the market. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to specific embodiments shown in the accompanying drawings.

[0027] See Figure 1 As shown, the present invention provides a method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication. This calculation method includes the following steps:

[0028] Step S1: Collect the input data required for modeling the main bearing shell EHD and connecting rod bearing shell EHD, and the main oil passage supply pressure data verified by sufficient reliability tests. Since the reliability test has been verified, the pressure is considered to meet the bearing shell cooling and lubrication requirements.

[0029] Step S2: Convert the main oil passage supply pressure into the oil supply pressure at the connecting rod bearing;

[0030] Step S3: Establish the connecting rod bearing EHD model and the main bearing EHD model respectively. The main bearing EHD model is subjected to the main oil passage oil supply pressure, and the connecting rod bearing EHD model is loaded with the converted connecting rod bearing oil supply pressure. After loading the oil supply pressure, the connecting rod bearing EHD and main bearing EHD models have cooling and lubrication effects.

[0031] Step S4: Perform EHD calculations for the main bearing shell and connecting rod bearing shell under external characteristic conditions, and obtain the temperature rise results of the oil at the main bearing shell and connecting rod bearing shell and the bearing shell lubrication results. The external characteristic conditions are the maximum load at a specific speed. If the temperature rise results and bearing shell lubrication results obtained in this way meet the requirements, they will naturally meet the requirements under low load.

[0032] Step S5: Evaluate whether the current temperature rise and bearing lubrication results meet the evaluation criteria; determine whether the current pressure meets the requirements, and verify the accuracy of the model and data.

[0033] Step S6: By comparing the oil temperature rise results of the main bearing and connecting rod bearing, it is determined that subsequent work will be carried out based on the connecting rod bearing EHD model. The oil supply pressure mainly affects the oil temperature rise of the bearing. Generally, the oil temperature rise of the connecting rod bearing will be much greater than that of the main bearing. Therefore, the connecting rod bearing EHD model is selected for subsequent experiments.

[0034] Step S7: Perform EHD calculations for the connecting rod bearing under partial load at different speeds, calculate the oil supply pressure of the connecting rod bearing under the load test state, and obtain the oil temperature rise result of the connecting rod bearing under partial load. This temperature rise result is generally lower than the external characteristic load condition at the corresponding speed, which can reduce the flow rate of the oil pump and reduce the oil supply pressure of the bearing, thereby reducing the friction power of the bearing and reducing the friction power loss of the whole machine.

[0035] Step S8 reduces the oil supply pressure and performs EHD calculations for the connecting rod bearing under partial load at different speeds. When the temperature rise increases to the corresponding external characteristic temperature rise result at the speed, the reduced oil supply pressure is the recommended minimum oil supply pressure value for cooling and lubrication of the main bearing and connecting rod bearing under this partial load condition. Based on the external characteristic oil supply pressure that has passed the reliability test, the oil pressure under this condition is not adjusted. Instead, the minimum oil supply pressure requirement under full operating conditions is determined by reducing the oil supply pressure under partial load. This serves as a reference for the selection of the oil pump. The minimum oil supply pressure can be effectively obtained through calculation without extensive testing, effectively saving product development time, reducing development costs, and improving economic efficiency to meet the development needs of rapid product updates.

[0036] Specifically, in step S1, the input data required for modeling includes engine performance parameters, engine component structural parameters, engine cylinder pressure, engine oil pressure, and engine oil temperature. The parameters are used to model the main bearing EHD and connecting rod bearing EHD, providing data support for subsequent calculations.

[0037] Furthermore, in step S4, the external characteristic operating condition is the 100% load condition of the engine operating across its entire speed range. If the temperature rise and bearing lubrication results obtained in this way meet the requirements, the reliability can be guaranteed when used as a reference in the future.

[0038] Furthermore, in step S6, the oil temperature rise of the connecting rod bearing is much greater than that of the main bearing. It is necessary to determine whether the connecting rod bearing EHD model is accurate so that the data can be accurately guaranteed in the future. Since the connecting rod bearing plays a major role in driving the piston to do work during engine operation, the force and work done are much greater than those at the main bearing, resulting in a higher oil temperature rise.

[0039] Furthermore, in step S7, the load conditions can be divided into 100%, 80%, 60%, 40%, 20%, and 0% load conditions. The minimum oil supply pressure for the corresponding working conditions is calculated. The calculation is performed for different working conditions and then written into the control system. The engine controls the oil pump to supply oil according to the minimum oil supply pressure corresponding to the working condition, thereby effectively reducing friction power.

[0040] Furthermore, in step S7, the values ​​of different speeds are taken at intervals of 20% to 30% within the engine's speed range, from the maximum value to the minimum value. Through the calculation of different speeds, precise control under different speeds and load conditions can be achieved, which maximizes the reduction of friction power.

[0041] Furthermore, in step S8, the partial load temperature rise value is compared with the external characteristic temperature rise value, and the oil supply pressure is adjusted according to the difference value. Each oil supply pressure drop does not exceed 2 bar. By adjusting the oil supply pressure in a stepwise manner, the minimum oil supply pressure can be quickly obtained, effectively shortening the calculation time and improving development efficiency.

[0042] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention, and these will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication, characterized in that, This calculation method includes the following steps: Step S1: Collect input data that meets the modeling requirements of main bearing EHD and connecting rod bearing EHD and main oil passage supply pressure data verified through sufficient reliability tests; Step S2: Convert the main oil passage supply pressure into the oil supply pressure at the connecting rod bearing; Step S3: Establish the connecting rod bearing EHD model and the main bearing EHD model respectively. The main bearing EHD model is subjected to the main oil passage supply pressure, and the connecting rod bearing EHD model is loaded with the converted connecting rod bearing supply pressure. Step S4: Perform EHD calculations for the main bearing shell and connecting rod bearing shell under external characteristic working conditions, and obtain the oil temperature rise results and bearing lubrication results at the main bearing shell and connecting rod bearing shell. Step S5: Evaluate whether the current temperature rise and bearing lubrication results meet the evaluation criteria; Step S6: By comparing the oil temperature rise results of the main bearing and connecting rod bearing, it is determined that subsequent work will be carried out based on the connecting rod bearing EHD model; Step S7: Perform EHD calculations for the connecting rod bearing under partial load at different speeds, calculate the oil supply pressure of the connecting rod bearing under the load test state, and obtain the oil temperature rise results of the connecting rod bearing under partial load. Step S8: Reduce the oil supply pressure and perform EHD calculations for the connecting rod bearing under partial load at different speeds. When the temperature rise increases to the external characteristic temperature rise result at the corresponding speed, the reduced oil supply pressure is the recommended minimum oil supply pressure value to meet the cooling and lubrication of the main bearing and connecting rod bearing under this partial load condition.

2. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S1, the input data required for modeling includes engine performance parameters, engine component structural parameters, engine cylinder pressure, engine oil pressure, and engine oil temperature.

3. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S4, the external characteristic condition refers to the 100% load condition during the engine's operation across its entire speed range.

4. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S6, the oil temperature rise at the connecting rod bearing will be much greater than that at the main bearing. It is necessary to determine whether the connecting rod bearing EHD model is accurate so that the data can be accurately guaranteed when using the connecting rod bearing EHD model in the future.

5. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S7, the load conditions can be divided into 100%, 80%, 60%, 40%, 20%, and 0% load conditions, and the minimum oil supply pressure for the corresponding working conditions is calculated.

6. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S7, the values ​​of different speeds are taken at intervals of 20% to 30% within the engine's speed range, from the maximum value to the minimum value.

7. The method for calculating the minimum oil supply pressure of the main oil passage for bearing cooling and lubrication according to claim 1, characterized in that, In step S8, the partial load temperature rise value is compared with the external characteristic temperature rise value, and the oil supply pressure is adjusted according to the difference value, with each oil supply pressure drop not exceeding 2 bar.

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