Method, system and motor vehicle for the pressure control of lubricating oil

Abstract

The present application relates to the pressure control method, system and motor vehicle of lubricating oil, according to the rotational speed, torque, main oil passage pressure and target main oil passage pressure MAP and demand lubricating oil flow MAP of engine, obtain the demand lubricating oil flow of bearing under target main oil passage pressure;According to the main oil passage pressure difference control lubricating oil power device output lubricating oil flow meets the demand of bearing and makes the main oil passage pressure difference maintain in the set range;According to the temperature of piston cooling nozzle under the current working condition, the corresponding demand lubricating oil flow is obtained, the target lubricating oil pressure of piston cooling nozzle under the corresponding working condition is obtained based on the pressure flow curve, and the flow of lubricating oil passing through piston cooling nozzle is controlled to meet the demand and make the pressure difference maintain in the set range according to the lubricating oil pressure difference of piston cooling nozzle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engine control, in particular to a lubricating oil pressure control method, system and motor vehicle. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The engine lubricating oil pressure control is traditionally achieved by adjusting the lubricating oil power device and the corresponding electric control proportional valve to change the flow rate to realize the pressure control according to the difference between the collected main oil passage pressure and the target main oil passage pressure. The pressure control of this method has large fluctuation, and there are multiple parts in the lubricating system that need to be lubricated, for example, the lubricating oil passes through the bearing to ensure the performance of the bearing, and also passes through the piston cooling nozzle to supply lubricating oil to cool the piston. The demand for pressure and flow rate of lubricating oil at each part may be different, and the traditional pressure control is not accurate, which affects the oil saving effect.

[0004] For example, under the engine part load condition, the heat load of the piston decreases, and the oil supply amount of the piston cooling nozzle can be appropriately reduced, but the oil supply amount of the piston cooling nozzle is irrelevant to the engine load, and if the flow rate of the piston cooling nozzle is maintained unchanged at a certain speed, the piston may be over-cooled, which indirectly causes the waste of lubricating oil nozzle flow rate and energy. SUMMARY

[0005] To solve the technical problems in the background art, the present application provides a lubricating oil pressure control method, system and motor vehicle, which improves the accurate control of the main oil passage pressure by collecting the lubricating oil flow rate, the main oil passage pressure and the piston cooling nozzle lubricating oil pressure.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0007] The first aspect of the present application provides a lubricating oil pressure control method, comprising the following steps:

[0008] Obtaining the speed, torque and main oil passage pressure under the current working condition of the engine, and obtaining the target main oil passage pressure under the corresponding speed and torque according to the target main oil passage pressure MAP;

[0009] According to the difference ΔP between the current working condition main oil passage pressure and the target main oil passage pressure, and the demand lubricating oil flow rate MAP, controlling the lubricating oil flow rate output by the lubricating oil power device to maintain the pressure difference ΔP within the set range;

[0010] The piston's current operating temperature is obtained, leading to the corresponding required lubricating oil flow rate. Based on a pre-set pressure-flow curve, the target lubricating oil pressure for the piston cooling nozzle under the corresponding operating conditions is calculated. The difference ΔP between the current lubricating oil pressure and the target lubricating oil pressure at the piston cooling nozzle is then used to determine the optimal lubricating oil pressure. pcj Controlling the flow rate of lubricating oil through the piston cooling nozzle, so that ΔP pcj Maintain within the set range.

[0011] Furthermore, the lubricating oil flow rate output by the lubricating oil power unit shall first satisfy the pressure difference value ΔP. On the basis of satisfying the pressure difference value ΔP, a deviation between the flow rate output by the lubricating oil power unit and the flow rate obtained by querying the required lubricating oil flow rate MAP is allowed.

[0012] Furthermore, based on the pressure difference ΔP between the current main oil passage pressure and the target main oil passage pressure, and the required lubricating oil flow rate MAP, the output lubricating oil flow rate of the lubricating oil power unit is controlled to maintain the pressure difference ΔP within the set range, specifically:

[0013] Obtain the main oil passage pressure P and the target main oil passage pressure P T ;

[0014] When P > P T And ΔP=PP T When the flow rate exceeds the upper limit, reduce the output flow rate of the lubricating oil power unit;

[0015] When P < P T And ΔP=PP T When the flow rate decreases to below the lower limit, increase the output flow rate of the lubricating oil power unit.

[0016] Furthermore, based on the difference ΔP between the current lubricating oil pressure and the target lubricating oil pressure of the piston cooling nozzle... pcj Controlling the flow rate of lubricating oil through the piston cooling nozzle, so that ΔP pcj Maintain within the set range, specifically:

[0017] Obtain the lubricating oil pressure P pcj With the target lubricating oil pressure P T-pcj ;

[0018] When P pcj >P T-pcj And ΔP pcj =P pcj -P T-pcj When the value increases beyond the upper limit, reduce the flow rate of lubricating oil delivered to the piston cooling nozzle;

[0019] When P pcj <P T-pcj And ΔPpcj = P pcj - P T-pcj When the reduction exceeds the lower limit value, the flow of lubricating oil into the piston cooling nozzle is increased.

[0020] Further, the target main oil passage pressure MAP is determined based on experiments by measuring the bearing temperature at different engine speeds and torques, and the target main oil passage pressure is determined when the bearing temperature is below the limit value and there is no cavitation phenomenon, and the target main oil passage pressure MAP is obtained by fitting the experimental data.

[0021] Further, the required lubricating oil flow MAP includes:

[0022] By simulation, the required lubricating oil flow of the bearing at different engine speeds, torques and main oil passage pressures is obtained;

[0023] By experiment, the relationship between the piston temperature and the piston cooling nozzle flow, engine speed and torque is measured, and the required lubricating oil flow of the piston cooling nozzle at different engine speeds and torques is obtained according to the temperature limit value of the piston material;

[0024] The required lubricating oil flow of the bearing and the required lubricating oil flow of the piston cooling nozzle are fitted to obtain the required lubricating oil flow MAP.

[0025] The second aspect of the present application provides a lubricating oil pressure control system, comprising:

[0026] The lubricating system includes an oil sump for storing lubricating oil, a lubricating oil power device for providing power to the stored lubricating oil, and two oil paths of a main oil passage and a secondary oil passage, which return to the oil sump after passing through the bearing and the piston, respectively, and the lubricating oil enters the piston;

[0027] The pressure control system comprises:

[0028] A flow sensor is used to obtain the flow of lubricating oil output by the lubricating oil power device;

[0029] A main oil passage pressure sensor is used to obtain the pressure of the lubricating oil flowing through the main oil passage;

[0030] A secondary oil passage pressure sensor is used to obtain the pressure of the lubricating oil flowing through the secondary oil passage;

[0031] An electrically controlled proportional valve is used to adjust the flow of lubricating oil into the piston through the piston cooling nozzle by changing the opening degree;

[0032] The first ECU control module is configured to: acquire the engine speed, torque and main oil passage pressure under the current operating conditions; obtain the target main oil passage pressure at the corresponding speed and torque according to the target main oil passage pressure MAP; and control the output lubricating oil flow rate of the lubricating oil power unit to meet the bearing's required lubricating oil flow rate and maintain the pressure difference ΔP within the set range according to the difference ΔP between the current operating conditions and the target main oil passage pressure, as well as the required lubricating oil flow rate MAP.

[0033] The second ECU control module is configured to: acquire the piston's current operating temperature, obtain the corresponding required lubricating oil flow rate, and, based on a pre-set pressure-flow curve, obtain the target lubricating oil pressure of the piston cooling nozzle under the corresponding operating condition, and calculate the difference ΔP between the current lubricating oil pressure and the target lubricating oil pressure of the piston cooling nozzle. pcj Controlling the flow rate of lubricating oil through the piston cooling nozzle, so that ΔP pcj Maintain within the set range.

[0034] Furthermore, based on the difference between the main oil passage pressure and the target main oil passage pressure, the current flow rate output by the lubricating oil power unit is changed, specifically as follows:

[0035] Obtain the main oil passage pressure P and the target main oil passage pressure P T ;

[0036] When P > P T And ΔP=PP T When the flow rate exceeds the upper limit, reduce the output flow rate of the lubricating oil power unit;

[0037] When P < P T And ΔP=PP T When the flow rate decreases to below the lower limit, increase the output flow rate of the lubricating oil power unit.

[0038] Furthermore, by utilizing the pressure difference between the target lubricating oil pressure and the pressure at the piston cooling nozzle, the opening of the electronically controlled proportional valve is changed to adjust the flow rate of lubricating oil delivered to the piston cooling nozzle, specifically as follows:

[0039] Obtain the lubricating oil pressure P pcj With the target lubricating oil pressure P T-pcj ;

[0040] When P pcj >P T-pcj And ΔP pcj =P pcj -P T-pcj When the value increases beyond the upper limit, the opening of the electronically controlled proportional valve is reduced.

[0041] When P pcj <P T-pcj And ΔPpcj = P pcj - P T-pcj When the reduction exceeds the lower limit value, the opening of the electric control proportional valve is increased.

[0042] A third aspect of the present application provides an engine having a lubrication system installed with the above pressure control system.

[0043] A fourth aspect of the present application provides a motor vehicle installed with the above engine.

[0044] Compared with the prior art, the above one or more technical solutions have the following beneficial effects:

[0045] 1. The demand lubricating oil flow of the bearing and the piston cooling nozzle of the lubrication system is considered simultaneously, the total flow output by the lubricating oil power device is controlled by using the target main oil passage pressure MAP and the demand lubricating oil flow MAP, and it is ensured that the demand flow of the piston cooling nozzle can be met on the basis of meeting the demand flow of the bearing; at the same time, the demand lubricating oil flow of the piston is obtained through the current working condition, the flow of the piston cooling nozzle lubricating oil is controlled to realize pressure regulation, the pressure of the main oil passage is indirectly controlled, the control accuracy of the pressure of the main oil passage is improved, energy waste is reduced, and the oil saving effect is improved.

[0046] 2. The demand lubricating oil flow MAP is obtained by fitting two parts of data, i.e., the demand lubricating oil flow of the bearing obtained through simulation and the demand lubricating oil flow of the piston cooling nozzle obtained through experiment, and the flow demand of the bearing and the piston nozzle can be met simultaneously, and the flow demand calculated according to the current temperature of the piston is combined with the pressure-flow curve, so that the piston nozzle can be maintained in the required pressure difference range, thereby the oil supply is appropriately changed according to the actual temperature condition, the overcooling phenomenon is improved, and energy consumption is saved. BRIEF DESCRIPTION OF DRAWINGS

[0047] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application.

[0048] Figure 1 is a pressure control schematic diagram of lubricating oil provided by one or more embodiments of the present application;

[0049] Figure 2 is a control process schematic diagram of a lubricating oil power device and an electric control proportional valve provided by one or more embodiments of the present application.

[0050] In the diagram: 1 Oil pan, 2 Lubricating oil power unit, 3 Flow meter, 4 Filter and cooler, 5 Main oil passage, 6 Bearing, 7 Auxiliary oil passage, 8 Electronic proportional valve, 9 Piston cooling nozzle, 10 First ECU control module, 11 Second ECU control module, 12 Piston cooling oil pressure sensor, 13 Main oil passage oil pressure sensor. Detailed Implementation

[0051] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0052] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0053] MAP refers to the control curve of a motor vehicle. For example, the MAP of an electric motor is an ignition control curve that reflects the distribution of motor efficiency at different speeds and torques. Similarly, the lubricating oil flow MAP is obtained by measuring the temperature of the lubricated parts under different engine speeds and torques through experiments or simulations. Within a certain temperature limit, the lubricating oil flow rate is determined. Multiple sets of data points are obtained through repeated experiments or simulations, and the corresponding control curve is obtained after fitting. This curve is then loaded into the corresponding controller to control the corresponding components.

[0054] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the scope of exemplary embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0055] As described in the background section, the traditional method adjusts the lubricating oil power unit and the corresponding electronically controlled proportional valve by measuring the difference between the collected main oil passage pressure and the target main oil passage pressure. This method results in large pressure fluctuations and inaccurate pressure control, which affects the fuel-saving effect.

[0056] Therefore, the following embodiments provide a method, system, and vehicle for controlling the pressure of lubricating oil, which improves the accurate control of the main oil passage pressure by collecting lubricating oil flow rate, main oil passage pressure, and piston cooling nozzle lubricating oil pressure.

[0057] Example 1:

[0058] like Figures 1-2 As shown, the method for controlling the pressure of lubricating oil includes the following steps:

[0059] The current speed, torque and main oil passage pressure of the engine are obtained, and the target main oil passage pressure corresponding to the speed and torque is obtained according to the target main oil passage pressure MAP;

[0060] The difference ΔP between the current main oil passage pressure and the target main oil passage pressure is obtained according to the current working condition, and the lubricating oil flow rate output by the lubricating oil power device is controlled according to the required lubricating oil flow rate MAP, so that the pressure difference ΔP is maintained within a set range.

[0061] The temperature of the piston under the current working condition is obtained, and the corresponding required lubricating oil flow rate is obtained. Based on the pre-set pressure flow curve, the target lubricating oil pressure of the piston cooling nozzle under the corresponding working condition is obtained. According to the difference ΔP between the current lubricating oil pressure of the piston cooling nozzle and the target lubricating oil pressure pcj , the flow rate of the lubricating oil passing through the piston cooling nozzle is controlled, so that ΔP pcj is maintained within a set range.

[0062] The lubricating oil power device of the engine lubricating system is used to pressurize and provide flow rate (such as an oil pump) for the lubricating oil, which can adjust the lubricating oil flow rate according to the engine working condition, reduce the power consumption of the lubricating oil power device itself, and also reduce the oil consumption.

[0063] In this embodiment, as shown in Figure 1 , the lubricating system includes a main oil passage 5 and a secondary oil passage 7. The oil sump 1 stores lubricating oil and receives returned lubricating oil. The lubricating oil power device 2 provides power to the stored lubricating oil, which is divided into the main oil passage 5 and the secondary oil passage 7 after passing through the flow meter 3.

[0064] In this embodiment, the lubricating oil is filtered and cooled by the filter and cooler 4 after passing through the flow meter 3, and then is divided into the main oil passage 5 and the secondary oil passage 7. The filter and cooler 4 is a conventional component, and this embodiment will not be described in detail.

[0065] The main oil passage 5 returns to the oil sump 1 after passing through the set lubricating parts, and the main oil passage pressure obtained by the main oil passage pressure sensor 13 during the period is used to control the parameters of the lubricating oil power device 2 through the first ECU control module 10, so as to change the lubricating oil flow rate and pressure.

[0066] In this embodiment, the lubricating parts passed by the main oil passage 5 are bearings 6. The required lubricating oil flow rate of the bearings 6 is related to the bearing diameter, bearing gap, bearing number, lubricating oil viscosity, etc. The target main oil passage pressure MAP of the engine under different speeds and torques and the required lubricating oil flow rate MAP of the lubricating oil power device are stored in the first ECU control module 10.

[0067] The lubricating oil flow collected by the flow meter 3 is used to control the flow of the lubricating oil power device according to the required lubricating oil flow, and the first ECU control module 10 is used to control the flow of the lubricating oil power device in a closed loop according to the difference between the main oil passage pressure collected by the sensor and the target main oil passage pressure.

[0068] In this embodiment, the closed loop flow control includes the following steps:

[0069] The engine speed and torque are obtained, the required lubricating oil flow MAP of the lubricating oil power device is queried, the required lubricating oil flow of the bearing is obtained, the engine main oil passage pressure P is obtained, and the difference between the target main oil passage pressure P T is controlled by PID to maintain the difference within a set range; when P>P T , and ΔP=P-P T increases to exceed the upper limit value, the flow of the lubricating oil power device is reduced, and when ΔP falls below the upper limit value, the current flow is maintained; when P T , and ΔP=P-P T decreases to exceed the lower limit value, the flow is increased, and when ΔP exceeds the lower limit value, the current flow is maintained.

[0070] Since the required lubricating oil flow MAP is predetermined, the priority of ΔP is higher than that of the required lubricating oil flow MAP, and the flow output by the lubricating oil power device is prioritized to meet ΔP. On the basis of meeting ΔP, the flow output by the lubricating oil power device may deviate from the flow obtained by querying the required lubricating oil flow MAP. At this time, ΔP is prioritized, and the deviation between the flow output by the lubricating oil power device and the flow obtained by querying the required lubricating oil flow MAP is allowed.

[0071] The target main oil passage pressure MAP is derived from experiments. By measuring the bearing temperature of the engine under different speeds and torques, it is detected whether there is cavitation phenomenon on the bearing surface. When the bearing temperature limit value is below and there is no cavitation phenomenon, the target main oil passage pressure is determined. Through several experiments on a certain type of engine, the target main oil passage pressure under the corresponding working condition is obtained.

[0072] The required lubricating oil flow MAP is obtained by the following steps:

[0073] One-dimensional shafting simulation is performed by simulation software (such as AVL EXCITE software) to obtain the required lubricating oil flow of the bearing under the target main oil passage pressure;

[0074] Through experiments, the relationship between the piston temperature and the piston cooling nozzle flow, the engine speed and the torque is measured, and according to the temperature limit value of the piston material, the required lubricating oil flow of the piston cooling nozzle under different engine speeds and torques is obtained;

[0075] The required lubricating oil flow of the bearing and the required lubricating oil flow of the piston cooling nozzle are fitted to obtain a required lubricating oil flow MAP.

[0076] The sub-oil gallery 7 returns to the oil pan 1 after passing through the set lubricating position, and in this embodiment, the position passed through by the sub-oil gallery 7 is the piston. The lubricating oil returns to the oil pan 1 after passing through the electric proportional valve 8 and the piston cooling nozzle 9 in sequence, the pressure of the lubricating oil at this position is obtained by using the piston cooling oil pressure sensor 12, and the second ECU control module 11 is used to control the electric proportional valve 8 to change the opening degree, so as to control the lubricating oil flow and pressure output by the piston cooling nozzle 9.

[0077] The target lubricating oil pressure of the piston cooling nozzle is obtained through the required lubricating oil flow of the piston and the pressure flow curve of the nozzle, and the difference between the lubricating oil pressure of the piston cooling nozzle collected by the piston cooling oil pressure sensor 12 and the target lubricating oil pressure is used to adjust the opening degree of the electric proportional valve 8 by the second ECU control module 11.

[0078] In this embodiment, the opening degree adjustment of the electric proportional valve 8 includes the following steps:

[0079] The collected lubricating oil pressure P pcj The difference between the target lubricating oil pressure P T-pcj , so that the difference between the two is maintained within a set range, and the control is performed by PID;

[0080] When P pcj >P T-pcj , and ΔP pcj =P pcj -P T-pcj increases to exceed the upper limit value, the opening degree of the electric proportional valve is reduced;

[0081] When P pcj <P T-pcj , and ΔP pcj =P pcj -P T-pcj decreases to exceed the lower limit value, the opening degree of the electric proportional valve is increased.

[0082] It should be noted that in the actual lubricating oil pressure control process, the flow is difficult to collect, and usually only the total flow of the entire lubricating system can be collected, while the pressure signal and the temperature signal are relatively easier to collect, and the real-time value can be directly read, which is more conducive to control, therefore, the control logic is usually taken as the flow control object, and the final purpose is still pressure control, which is a common phenomenon in the field.

[0083] It should be noted that for the engine, the bearing and the piston are the two main parts that need to control the flow of lubricating oil (or pressure), and the rest of the parts have less demand for flow compared to the two parts. Here, only for the sake of understanding the scheme, the applicable scenarios are simplified.

[0084] As shown in Figure 1 The lubricating system includes a main oil passage 5 and a secondary oil passage 7, and the oil supply amount of the piston cooling nozzle 9 in the secondary oil passage 7 is used to cool the engine piston. In the part load condition of the engine, the thermal load of the piston decreases, and the oil supply amount of the piston cooling nozzle 9 can be appropriately reduced. However, the oil supply amount is irrelevant to the engine load, and if the flow of the piston cooling nozzle 9 is unchanged at a certain speed, the piston may be over-cooled with the change of the load, thereby causing waste of nozzle flow. By arranging an electric proportional valve 8 on the secondary oil passage before the piston cooling nozzle, the flow of the piston cooling nozzle is adjusted to avoid over-cooling of the piston, thereby reducing energy waste.

[0085] In the method given in the embodiment, the target main oil passage pressure MAP and the required lubricating oil flow MAP are obtained by experiments and simulations in advance. The required lubricating oil flow MAP obtains the required lubricating oil flow of the bearing at a certain target main oil passage pressure and the required lubricating oil flow of the corresponding piston cooling nozzle. That is, on the basis of having met the required lubricating oil flow of the bearing, the required lubricating oil flow of the piston cooling nozzle is obtained.

[0086] This way takes into account the required lubricating oil flow of the bearing and the piston cooling nozzle in the lubricating system. The required lubricating oil flow of the bearing obtained by the required lubricating oil flow MAP, combined with the main oil passage pressure difference, can make the total flow output by the lubricating oil power device meet the requirements of the bearing and the piston cooling nozzle. However, the required lubricating oil flow of the piston cooling nozzle here is derived from the required lubricating oil flow of the bearing and the corresponding engine operating condition, and the over-cooling phenomenon introduced in the background art may occur, causing energy waste.

[0087] Therefore, according to the current temperature of the piston, the required lubricating oil flow of the piston cooling nozzle is obtained (usually by table lookup), and the required flow of the piston cooling nozzle here (by table lookup) is combined with the pressure-flow curve obtained by pre-experiment to obtain the target pressure of the piston cooling nozzle. Then, the opening of the electric proportional valve is controlled according to the difference between the current lubricating oil pressure, so that the lubricating oil flow through the piston cooling nozzle is controlled according to the required lubricating oil flow under its current operating condition, instead of the required flow in the required lubricating oil flow MAP in the early stage, thereby improving the over-cooling phenomenon and saving energy consumption.

[0088] Embodiment two:

[0089] The pressure control system of the lubricating oil comprises:

[0090] The lubrication system includes an oil pan 1 for storing lubricating oil, a lubricating oil power unit 2 for supplying power to the stored lubricating oil, and two oil passages, a main oil passage 5 and a secondary oil passage 7, which return to the oil pan after passing through the bearing and piston respectively, and the lubricating oil enters the piston.

[0091] Pressure control system, including:

[0092] A flow sensor is used to obtain the flow rate of lubricating oil output by the lubricating oil power unit;

[0093] The main oil passage pressure sensor is used to obtain the pressure of lubricating oil flowing through the main oil passage;

[0094] The auxiliary oil passage pressure sensor is used to obtain the pressure of lubricating oil flowing through the auxiliary oil passage;

[0095] An electronically controlled proportional valve adjusts the flow rate of lubricating oil delivered to the piston through the piston cooling nozzle by changing its opening degree.

[0096] The first ECU control module is configured to: acquire the engine speed, torque and main oil passage pressure under the current operating conditions; obtain the target main oil passage pressure at the corresponding speed and torque according to the target main oil passage pressure MAP; control the output lubricating oil flow of the lubricating oil power unit to meet the bearing's required lubricating oil flow according to the difference ΔP between the current operating conditions and the target main oil passage pressure, and according to the required lubricating oil flow MAP, and maintain the pressure difference ΔP within the set range.

[0097] The second ECU control module is configured to: acquire the piston's current operating temperature, obtain the corresponding required lubricating oil flow rate, and, based on a pre-set pressure-flow curve, obtain the target lubricating oil pressure of the piston cooling nozzle under the corresponding operating condition, and calculate the difference ΔP between the current lubricating oil pressure and the target lubricating oil pressure of the piston cooling nozzle. pcj Controlling the flow rate of lubricating oil through the piston cooling nozzle, so that ΔP pcj Maintain within the set range.

[0098] Meanwhile, the required lubricating oil flow rate of the bearing and piston cooling nozzle in the lubrication system is also considered. The required lubricating oil flow rate of the bearing is obtained by using the required lubricating oil flow rate MAP. Combined with the pressure difference of the main oil passage, the total flow rate output by the lubricating oil power unit can meet the needs of the bearing and piston cooling nozzle. However, the lubricating oil flow rate requirement of the piston cooling nozzle here comes from the lubricating oil flow rate requirement of the bearing and the corresponding engine operating conditions. This may lead to the overcooling phenomenon described in the background technology, resulting in energy waste.

[0099] Therefore, according to the current temperature of the piston cooling nozzle, the required lubricating oil flow of the piston cooling nozzle is obtained (usually by table lookup), the required flow of the piston cooling nozzle (table lookup) is used herein, the target pressure of the piston cooling nozzle is obtained by combining the pressure-flow curve obtained by prior experiments, and the opening of the electric control proportional valve is controlled by combining the difference between the current lubricating oil pressure, so that the lubricating oil flow through the piston cooling nozzle is controlled according to the required lubricating oil flow under the current working condition, instead of the required flow in the previous required lubricating oil flow MAP, thereby improving the over-cooling phenomenon and saving energy consumption.

[0100] Embodiment three:

[0101] A motor vehicle has a lubricating system installed with the pressure control system described above, which improves the fluctuation problem of lubricating oil pressure control, improves the accuracy of pressure control, and improves the fuel saving effect.

[0102] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A pressure control method for lubricating oil, characterized by, The method comprises the following steps: obtaining the speed, torque and main oil passage pressure of the engine under the current working condition, and obtaining the target main oil passage pressure corresponding to the speed and torque according to the target main oil passage pressure map; controlling the lubricating oil flow rate output by the lubricating oil power device according to the difference ΔP between the main oil passage pressure under the current working condition and the target main oil passage pressure and the demand lubricating oil flow rate map, so that the difference ΔP is maintained within a set range; acquire the temperature of the piston under the current working condition, obtain the corresponding required lubricating oil flow, based on the pre-set pressure flow curve, obtain the target lubricating oil pressure of the piston cooling nozzle under the corresponding working condition, according to the difference ΔP between the lubricating oil pressure of the piston cooling nozzle under the current working condition and the target lubricating oil pressure, control the flow of the lubricating oil passing through the piston cooling nozzle, so as to maintain ΔP in the set range pcj . pcj ​ wherein the demand lubricating oil flow rate map comprises the following steps: obtaining the demand lubricating oil flow rate of the bearing under different speeds, torques and main oil passage pressures of the engine through simulation; measuring the relationship between the piston temperature and the piston cooling nozzle flow rate, the engine speed and the torque through experiment, and obtaining the demand lubricating oil flow rate of the piston cooling nozzle under different speeds and torques of the engine according to the temperature limit value of the piston material; fitting the demand lubricating oil flow rate of the bearing and the demand lubricating oil flow rate of the piston cooling nozzle to obtain the demand lubricating oil flow rate map; wherein the lubricating oil power device provides power to the stored lubricating oil, and is divided into a main oil passage and a secondary oil passage, and returns to the oil sump after passing through the bearing and the piston respectively.

2. The pressure control method of lubricating oil according to claim 1, characterized by, The lubricating oil flow rate output by the lubricating oil power device is preferentially used to satisfy the difference ΔP, and on the basis of satisfying the difference ΔP, a deviation is allowed to exist between the flow rate output by the lubricating oil power device and the flow rate obtained by querying the demand lubricating oil flow rate map.

3. The pressure control method of lubricating oil according to claim 1, characterized by, controlling the lubricating oil flow rate output by the lubricating oil power device according to the difference ΔP between the main oil passage pressure under the current working condition and the target main oil passage pressure and the demand lubricating oil flow rate map, so that the difference ΔP is maintained within a set range, specifically: acquiring a main gallery pressure P, and a target main gallery pressure P T ; When P > P T , and ΔP = P - P T , increase the flow rate of the lubricating oil power unit output; When P < P T , and ΔP = P - P T , increase the flow rate of the lubricating oil power unit output.

4. The pressure control method of lubricating oil according to claim 1, characterized by, According to the difference ΔP between the current lubricating oil pressure of the piston cooling nozzle and the target lubricating oil pressure pcj , the flow rate of the lubricating oil passing through the piston cooling nozzle is controlled, so that ΔP pcj is maintained within a set range, specifically: Acquiring a lubricating oil pressure P pcj With a target lubricating oil pressure P T-pcj ; When P pcj > P T-pcj , and ΔP pcj = P pcj - P T-pcj increases beyond an upper limit, the flow of lubricating oil to the piston cooling jets is reduced. When P pcj < P T-pcj , and ΔP pcj = P pcj - P T-pcj is reduced below a lower limit value, the flow of lubricating oil to the piston cooling jets is increased.

5. The pressure control method of lubricating oil according to claim 1, characterized by, the target main oil passage pressure map is based on experiment, and the target main oil passage pressure is determined by measuring the bearing temperature under different speeds and torques of the engine, when the bearing temperature is lower than the bearing temperature limit value and there is no cavitation phenomenon, and the target main oil passage pressure map is obtained by fitting the experimental data.

6. A pressure control system for lubricating oil for carrying out the method according to any one of claims 1 to 5, having an oil sump for storing the lubricating oil, a lubricating oil power unit for providing the stored lubricating oil with power, two oil circuits being divided into a main oil gallery and a secondary oil gallery, which return into the oil sump after passing through a bearing and a piston, respectively, and the lubricating oil enters the piston; characterized in that comprise: a flow rate sensor for obtaining the lubricating oil flow rate output by the lubricating oil power device; a main oil passage oil pressure sensor for obtaining the pressure of the lubricating oil flowing through the main oil passage; a secondary oil passage oil pressure sensor for obtaining the pressure of the lubricating oil flowing through the secondary oil passage; an electrically controlled proportional valve for adjusting the flow rate of the lubricating oil sent into the piston through the piston cooling nozzle by changing the opening degree; a first ECU control module for outputting an instruction for controlling the lubricating oil flow rate to the lubricating oil power device; a second ECU control module for outputting an instruction for changing the opening degree to the electrically controlled proportional valve to control the lubricating oil flow rate.

7. The pressure control system for lubricating oil according to claim 6, wherein The first ECU control module is configured to obtain the speed, torque and main oil passage pressure of the engine under the current working condition, obtain the target main oil passage pressure corresponding to the speed and torque according to the target main oil passage pressure map, control the lubricating oil flow rate output by the lubricating oil power device to satisfy the demand lubricating oil flow rate of the bearing according to the difference ΔP between the main oil passage pressure under the current working condition and the target main oil passage pressure and the demand lubricating oil flow rate map, and maintain the difference ΔP within a set range.

8. The pressure control system for lubricating oil according to claim 6, wherein The second ECU control module is configured to: acquire the temperature of the piston under the current working condition, obtain the corresponding required lubricating oil flow, obtain the target lubricating oil pressure of the piston cooling nozzle under the corresponding working condition based on the pre-set pressure-flow curve, and control the flow of the lubricating oil passing through the piston cooling nozzle according to the difference ΔP pcj between the lubricating oil pressure and the target lubricating oil pressure of the piston cooling nozzle under the current working condition, so that ΔP pcj is maintained within a set range.

9. Motor vehicle, characterized in that The pressure control system of the lubricating oil has any one of the lubricating oil pressure control systems according to claims 6-8.

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