Method for calculating minimum oil supply pressure of main oil duct meeting cooling and lubricating requirements of bearing bush

Abstract

The invention discloses a method for calculating the minimum oil supply pressure of a main oil duct meeting the requirement for bearing bush cooling and lubricating, belongs to the technical field of engines, and solves the problem that the minimum oil supply pressure of bearing bush cooling and lubricating cannot be calculated in the prior art. The calculation method comprises the steps that a connecting rod bearing bush EHD calculation model and a main bearing bush EHD calculation model are established respectively, a main oil duct oil supply pressure and a connecting rod bearing bush pressure are applied to a main bearing bush EHD model and a connecting rod bearing bush EHD model respectively, main bearing bush EHD calculation and connecting rod bearing bush EHD calculation under the external characteristic working condition are carried out respectively, and then partial load connecting rod EHD calculation under different rotating speeds is carried out. The oil supply pressure of the connecting rod bearing bush in the test state is loaded, the engine oil temperature rise result of the connecting rod bearing bush in the partial load state is obtained, the oil supply pressure is reduced, and when the temperature rise is increased to the external characteristic temperature rise result under the corresponding rotating speed, the calculated minimum oil supply pressure suggestion value meeting the bearing bush cooling and lubricating requirements under the partial load working condition is provided. According to the minimum oil supply pressure calculation method, the product development period is shortened, and the economical efficiency is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of engines, and in particular to a method for calculating the minimum oil supply pressure of a main oil channel that satisfies the cooling and lubrication requirements of a bearing bush. Background Art

[0002] The vigorous development of new energy has put forward more stringent requirements on the fuel economy of traditional engines. The friction power loss of the engine is an important factor affecting fuel economy, and the high-speed rotation of the crankshaft relative to the bearing will produce a large amount of friction loss, which accounts for a large proportion of the friction power loss of the whole engine.

[0003] In order to reduce the friction work of the bearing, in addition to changing the structural parameters of the bearing itself such as diameter, width, and bearing clearance, reducing the oil supply pressure of the bearing is also an important means to reduce friction work. After reducing the oil supply pressure, the required flow of the oil pump can be reduced. A smaller oil pump meets the cooling and lubrication requirements, and the friction loss of other components will be reduced accordingly. At the same time, the use of a small-flow oil pump can also achieve cost reduction and lightweight requirements. At present, there is no corresponding method and process for calculating the minimum oil supply pressure that meets the cooling and lubrication of the bearing. 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 channel that meets the cooling and lubrication requirements of the bearing shell in response to the above-mentioned deficiencies in the prior art, thereby saving product development cycle, reducing development costs, and effectively improving economic efficiency. The method has the characteristics of high economy and strong practicality.

[0005] The technical solution adopted by the present invention is: a method for calculating the minimum oil supply pressure of the main oil channel that meets the cooling and lubrication requirements of the bearing bush, and the calculation method comprises the following steps:

[0006] Step S1: collecting input data that meets the needs of main bearing EHD and connecting rod bearing EHD modeling and main oil gallery oil supply pressure data verified by sufficient reliability tests;

[0007] Step S2: converting the oil supply pressure of the main oil channel into the oil supply pressure at the connecting rod bearing;

[0008] Step S3: Establishing the connecting rod bearing EHD and main bearing EHD calculation models respectively, wherein the main bearing EHD model applies the main oil channel oil supply pressure, and the connecting rod bearing EHD model loads the converted connecting rod bearing oil supply pressure;

[0009] Step S4: performing calculations of the main bearing EHD and the connecting rod bearing EHD under the external characteristic conditions respectively, and obtaining the temperature rise results of the engine oil at the main bearing and the connecting rod bearing and the bearing lubrication results;

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

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

[0012] Step S7: Carry out partial load connecting rod EHD calculation at different speeds, load the connecting rod bearing oil supply pressure in the test state, and obtain the connecting rod bearing oil temperature rise result under the partial load state;

[0013] Step S8: Reduce the oil supply pressure and carry out partial load connecting rod EHD calculation 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 value of the calculated minimum oil supply pressure that meets the cooling and lubrication of the bearing under the partial load condition.

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

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

[0016] Furthermore, in step S6, the temperature rise of the connecting rod bearing oil will be much greater than the temperature rise of the main bearing oil, so as to determine whether the connecting rod bearing EHD model is accurate, so as to subsequently use the connecting rod EHD model to ensure data accuracy.

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

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

[0019] Furthermore, in the 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, and the oil supply pressure drop does not exceed 2 bar each time.

[0020] Beneficial Effects

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

[0022] (1) Taking the main oil channel oil pressure after completing the full reliability test as input, the EHD calculations of the main bearing and connecting rod bearing under the external characteristic condition are carried out respectively, and the EHD lubrication results and temperature rise results of the main bearing and connecting rod bearing are evaluated to determine whether the current pressure meets the requirements. The temperature rise results of the external characteristic condition that meet the evaluation standards can be effectively obtained, providing a reliable reference value for the subsequent oil supply pressure calculation.

[0023] (2) Taking the external characteristic oil supply pressure that has passed the reliability test as the benchmark, the oil pressure of this working condition is not adjusted. Instead, the oil supply pressure under partial load is reduced to finally determine the minimum oil supply pressure requirement under all working conditions. This is used as a reference for the selection of the oil pump. The minimum oil supply pressure can be effectively obtained through the calculation results without the need for a large number of tests, which effectively saves the product development cycle, reduces development costs, and improves economy to meet the development needs of rapid product updates.

[0024] (3) The minimum fuel supply pressure is confirmed by calculation, so it can be solidified only after further verification through testing. The dual guarantee of testing and calculation can avoid engine failure and shorten the development cycle, which is conducive to product market share. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

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

[0027] See also Figure 1 As shown, a method for calculating the minimum oil supply pressure of the main oil channel that meets the requirements of bearing cooling and lubrication of the present invention comprises the following steps:

[0028] Step S1: collecting input data that meets the needs of main bearing EHD and connecting rod bearing EHD modeling and main oil channel oil supply pressure data verified by sufficient reliability tests. Since the pressure has been verified by reliability tests, it is considered that it meets the requirements of bearing cooling and lubrication;

[0029] Step S2: converting the oil supply pressure of the main oil channel into the oil supply pressure at the connecting rod bearing;

[0030] Step S3: Establishing the connecting rod bearing EHD and main bearing EHD calculation models respectively, wherein the main bearing EHD model applies the main oil channel oil supply pressure, and the connecting rod bearing EHD model loads the converted connecting rod bearing oil supply pressure, and after loading the oil supply pressure, the connecting rod bearing EHD and main bearing EHD models have cooling and lubrication effects;

[0031] Step S4: Calculate the EHD of the main bearing and the connecting rod bearing under the external characteristic working condition, and obtain the temperature rise results and bearing lubrication results of the engine oil at the main bearing and the connecting rod bearing. The external characteristic working condition is the maximum load at a specific speed. If the temperature rise results and bearing lubrication results obtained in this way can meet the requirements, they will naturally meet the requirements under low load.

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

[0033] Step S6: By comparing the oil temperature rise results of the main bearing and the connecting rod bearing, it is determined that the subsequent work will be carried out based on the connecting rod 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 the oil temperature rise of the main bearing. Therefore, the connecting rod bearing EHD model is selected for subsequent experiments;

[0034] Step S7: Carry out partial load connecting rod EHD calculation at different speeds, load the connecting rod bearing oil supply pressure in the test state, and obtain the connecting rod bearing oil temperature rise result under the partial load state. The temperature rise result is generally lower than the external characteristic load condition under the corresponding speed, which can reduce the flow rate of the oil pump and 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 partial load connecting rod EHD calculations 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 value of the calculated minimum oil supply pressure for bearing cooling and lubrication under the partial load condition. The external characteristic oil supply pressure that passes the reliability test is used as a benchmark. The oil pressure of the condition is not adjusted. Instead, the partial load oil supply pressure is reduced to ultimately determine the minimum oil supply pressure requirement under the full condition. This is used as a reference for the selection of the oil pump. The minimum oil supply pressure can be effectively derived through the calculation results without the need for a large number of tests, which effectively saves the product development cycle, reduces development costs, and improves economy to meet the development needs of rapid product updates.

[0036] Specifically, in step S1, the input data required for modeling include engine performance parameters, structural parameters of engine components, 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 to provide data support for subsequent calculations.

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

[0038] Furthermore, in the step S6, the connecting rod bearing oil temperature rise will be much greater than the oil temperature rise at the main bearing, and whether the connecting rod bearing EHD model is accurate is determined so that the connecting rod EHD model can be used later to ensure data accuracy. Since the connecting rod bearing plays a major role in driving the piston to do work during engine operation, the force and work performed by the connecting rod bearing is much greater than that of the main bearing, and the oil temperature rise is higher.

[0039] Furthermore, in the step S7, the load state can be divided into 100%, 80%, 60%, 40%, 20%, and 0% load, and the minimum oil supply pressure of the corresponding working condition 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 according to the operating condition, thereby effectively reducing the friction power.

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

[0041] Furthermore, in the 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. The oil supply pressure drop does not exceed 2 bar each time. By adjusting the oil supply pressure in a step-by-step manner, the minimum oil supply pressure can be quickly obtained, which effectively shortens the calculation time and improves development efficiency.

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the structure of the present invention, which will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for calculating the minimum oil supply pressure of the main oil channel to meet the cooling and lubrication requirements of the bearing, characterized in that: This calculation method includes the following steps: Step S1: collecting input data that meets the needs of main bearing EHD and connecting rod bearing EHD modeling and main oil gallery oil supply pressure data verified by sufficient reliability tests; Step S2: converting the oil supply pressure of the main oil channel into the oil supply pressure at the connecting rod bearing; Step S3: Establishing the connecting rod bearing EHD and main bearing EHD calculation models respectively, wherein the main bearing EHD model applies the main oil channel oil supply pressure, and the connecting rod bearing EHD model loads the converted connecting rod bearing oil supply pressure; Step S4: performing calculations of the main bearing EHD and the connecting rod bearing EHD under the external characteristic conditions respectively, and obtaining the temperature rise results of the engine oil at the main bearing and the connecting rod bearing and the bearing lubrication results; Step S5: evaluating whether the current temperature rise result and bearing lubrication result meet the evaluation criteria; Step S6: By comparing the oil temperature rise results of the main bearing and the connecting rod bearing, it is determined that the subsequent work will be carried out based on the connecting rod EHD model; Step S7: Carry out partial load connecting rod EHD calculation at different speeds, load the connecting rod bearing oil supply pressure in the test state, and obtain the connecting rod bearing oil temperature rise result under the partial load state; Step S8: Reduce the oil supply pressure and carry out partial load connecting rod EHD calculation 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 value of the calculated minimum oil supply pressure that meets the cooling and lubrication of the bearing under the partial load condition.

2. A method for calculating the minimum oil supply pressure of the main oil passage that satisfies the cooling and lubrication of the bearing according to claim 1, characterized in that: In the step S1, the input data required for modeling include engine performance parameters, structural parameters of engine components, 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 that satisfies the cooling and lubrication of the bearing according to claim 1 is characterized in that: In the step S4, the external characteristic operating condition is a 100% load condition in the entire speed range of the engine.

4. The method for calculating the minimum oil supply pressure of the main oil passage that satisfies the cooling and lubrication of the bearing according to claim 1 is characterized in that: In step S6, the temperature rise of the connecting rod bearing oil will be much greater than the temperature rise of the main bearing oil, so as to determine whether the connecting rod bearing EHD model is accurate, so as to use the connecting rod EHD model to ensure data accuracy.

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

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

7. The method for calculating the minimum oil supply pressure of the main oil passage that satisfies the cooling and lubrication of the bearing according to claim 1 is characterized in that: In the 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, and the oil supply pressure drop does not exceed 2 bar each time.

Images