Engine oil pressure control method and device and vehicle

Abstract

The invention provides an engine oil pressure control method and device and a vehicle, and relates to the technical field of engines. The engine oil pressure control method comprises the steps that the upper limit engine oil temperature and the lower limit engine oil temperature corresponding to the obtained current engine oil temperature of an engine are determined in multiple continuous temperature intervals; performing interpolation calculation according to a first engine oil pressure corresponding to the current parameter of the engine at the upper limit engine oil temperature and a second engine oil pressure corresponding to the current parameter of the engine at the lower limit engine oil temperature, and determining an expected engine oil pressure corresponding to the current parameter of the engine at the current engine oil temperature; and according to the expected engine oil pressure, the engine oil pump control duty ratio is determined through a control algorithm, and the engine oil pump is controlled according to the engine oil pump control duty ratio. The duty ratio is controlled through the oil pump, and the oil pump can be dynamically controlled according to the operation state of the engine, so that the oil pump outputs the oil pressure meeting the requirement of the operation state of the engine, and the lubricating effect on the engine is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engines, and more particularly, to an engine oil pressure control method, device and vehicle. Background Art

[0002] As the power source of modern society, engines are applied in multiple fields such as transportation, industrial production and energy supply. In the transportation field, the application of engines is particularly significant. For example, various means of transportation such as cars, motorcycles, airplanes and ships all rely on different types of engines to achieve power conversion. During the operation of the engine, the lubricating effect of engine oil can effectively reduce the friction coefficient between various components, thereby reducing energy waste and improving the working efficiency of the engine.

[0003] When the operating state of the engine changes, the demand for lubrication effect and engine oil quantity also changes accordingly. However, the engine oil pressure in the conventional lubrication system is usually fixed, resulting in poor adaptability of the engine oil pressure to changes in the engine operating state and affecting the lubrication effect. Summary of the Invention

[0004] The problem to be solved by the present invention is how to improve the lubrication effect of the engine.

[0005] To solve the above problems, the present invention provides an engine oil pressure control method, device and vehicle.

[0006] In a first aspect, the present invention provides an engine oil pressure control method, including:

[0007] Determine a target temperature range corresponding to the current engine oil temperature of the engine obtained in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit engine oil temperature and a lower limit engine oil temperature;

[0008] Perform interpolation calculation based on a first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature and a second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature to determine an expected engine oil pressure corresponding to the current engine parameters at the current engine oil temperature, where the current engine parameters include the current engine speed and the current desired torque;

[0009] Determine the engine oil pump control duty ratio according to the expected engine oil pressure through a control algorithm, and control the engine oil pump according to the engine oil pump control duty ratio.

[0010] Optionally, before performing the interpolation calculation based on a first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature and a second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature, the engine oil pressure control method further includes:

[0011] Determine the first oil pressure matching relationship corresponding to the upper limit oil temperature and the second oil pressure matching relationship corresponding to the lower limit oil temperature respectively;

[0012] Determine the first oil pressure according to the current engine parameters in the first oil pressure matching relationship, and determine the second oil pressure according to the current engine parameters in the second oil pressure matching relationship, wherein the first oil pressure matching relationship and the second oil pressure matching relationship respectively include the corresponding relationship between the current engine parameters and the oil pressure at the corresponding temperature.

[0013] Optionally, the interpolation calculation is performed based on the first oil pressure corresponding to the current engine parameters at the upper limit oil temperature and the second oil pressure corresponding to the current engine parameters at the lower limit oil temperature to determine the desired oil pressure corresponding to the current engine parameters at the current oil temperature, including:

[0014] Determine the ratio of the difference between the current oil temperature and the lower limit oil temperature to the temperature width of the temperature range to obtain a first pressure proportionality factor; determine the ratio of the difference between the upper limit oil temperature and the current oil temperature to the temperature width to obtain a second pressure proportionality factor; wherein the temperature width is the difference between the upper limit oil temperature and the lower limit oil temperature;

[0015] Add the product of the first oil pressure and the first pressure proportionality factor and the product of the second oil pressure and the second pressure proportionality factor to obtain the desired oil pressure.

[0016] Optionally, determining the oil pump control duty ratio according to the desired oil pressure through a control algorithm includes:

[0017] Determine the target oil pressure range corresponding to the desired oil pressure in a plurality of consecutive oil pressure ranges, and perform interpolation calculation based on the first duty ratio corresponding to the upper limit oil pressure in the target oil pressure range at the current speed and the second duty ratio corresponding to the lower limit oil pressure in the target oil pressure range at the current speed to determine the feedforward control duty ratio corresponding to the current speed at the desired oil pressure;

[0018] Determine the closed-loop control duty ratio according to the acquired current actual oil pressure and the desired oil pressure;

[0019] Add the feedforward control duty ratio and the closed-loop control duty ratio to obtain the oil pump control duty ratio.

[0020] Optionally, before performing interpolation calculation based on the first duty ratio corresponding to the upper oil pressure of the target oil pressure range at the current rotational speed and the second duty ratio corresponding to the lower oil pressure of the target oil pressure range at the current rotational speed, the oil pressure control method further includes:

[0021] Determine the first duty ratio matching relationship corresponding to the upper oil pressure and the second duty ratio matching relationship corresponding to the lower oil pressure respectively;

[0022] Determine the first duty ratio according to the current oil temperature and the current rotational speed in the first duty ratio matching relationship, and determine the second duty ratio according to the current oil temperature and the current rotational speed in the second duty ratio matching relationship, where the first duty ratio matching relationship and the second duty ratio matching relationship include the corresponding relationships between the current oil temperature, the current rotational speed, and the duty ratio under the corresponding oil pressure.

[0023] Optionally, the interpolation calculation based on the first duty ratio corresponding to the upper oil pressure of the target oil pressure range at the current rotational speed and the second duty ratio corresponding to the lower oil pressure of the target oil pressure range at the current rotational speed to determine the feedforward control duty ratio corresponding to the current rotational speed at the desired oil pressure includes:

[0024] Determine the ratio of the difference between the desired oil pressure and the lower oil pressure to the pressure width of the oil pressure range to obtain a first duty ratio proportionality factor; determine the ratio of the difference between the upper oil pressure and the current oil pressure to the pressure width to obtain a second duty ratio proportionality factor, where the pressure width is the difference between the upper oil pressure and the lower oil pressure;

[0025] Add the product of the first duty ratio and the first duty ratio proportionality factor to the product of the second duty ratio and the second duty ratio proportionality factor to obtain the feedforward control duty ratio.

[0026] Optionally, determining the closed-loop control duty ratio according to the obtained current actual oil pressure and the desired oil pressure includes:

[0027] Determine the oil pressure desired deviation as the difference between the desired oil pressure and the desired oil pressure of the previous sampling period, multiply the ratio of the oil pressure desired deviation to the sampling period by a preset compensation coefficient after filtering to obtain a duty ratio compensation amount;

[0028] Determine the actual oil pressure deviation by taking the difference between the current actual oil pressure and the actual oil pressure in the previous sampling period obtained, multiply the ratio of the actual oil pressure deviation to the sampling period after the filtering process by a preset differential coefficient to obtain a differential duty ratio;

[0029] Determine the current oil pressure deviation by taking the difference between the current actual oil pressure and the desired oil pressure, and determine the proportional duty ratio as the product of the current oil pressure deviation and a preset proportional coefficient;

[0030] Sum the differences between the actual oil pressure and the desired oil pressure corresponding to each sampling period and multiply by a preset integral coefficient to obtain an initial integral duty ratio, and obtain the integral duty ratio by subtracting the product of a preset duty ratio overrun value and a correction coefficient from the initial integral duty ratio;

[0031] Add the duty ratio compensation amount, the differential duty ratio, the proportional duty ratio, and the integral duty ratio to obtain the closed-loop control duty ratio.

[0032] Optionally, the control method further includes:

[0033] Monitor the current actual oil pressure of the engine;

[0034] When the current actual oil pressure exceeds a preset stuck oil pressure range, determine that the oil pressure sensor is stuck; and / or,

[0035] Based on the current state of the engine, determine whether the current actual oil pressure is abnormal through the comparison result between the current actual oil pressure and a preset threshold.

[0036] Optionally, determining whether the current actual oil pressure is abnormal through the comparison result between the current actual oil pressure and a preset threshold includes:

[0037] When the engine is in the starting state, if the current actual oil pressure is less than a preset minimum boundary value, determine that the current actual oil pressure is abnormal;

[0038] When the engine is in the running state, if the current actual oil pressure is less than a preset minimum boundary value, determine that the current actual oil pressure is abnormal;

[0039] When the engine is in the starting state or the shutdown state, if the offset between the oil pressure sensor of the engine and the reference sensor exceeds a preset offset threshold range, determine that the current oil pressure is abnormal.

[0040] In a second aspect, the present invention provides an oil pressure control device, including:

[0041] A processing module, configured to determine a target temperature range corresponding to the currently obtained engine oil temperature in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit oil temperature and a lower limit oil temperature;

[0042] An interpolation calculation module, configured to perform interpolation calculation based on a first oil pressure corresponding to the current engine parameters at the upper limit oil temperature and a second oil pressure corresponding to the current engine parameters at the lower limit oil temperature, to determine an expected oil pressure corresponding to the current engine parameters at the current oil temperature, where the current engine parameters include the current engine speed and the current desired torque;

[0043] A control module, configured to determine an oil pump control duty ratio through a control algorithm based on the expected oil pressure, and control the oil pump according to the oil pump control duty ratio.

[0044] In a third aspect, the present invention provides a vehicle, including a memory and a processor;

[0045] The memory is configured to store a computer program;

[0046] The processor is configured to, when executing the computer program, implement the oil pressure control method as described in the first aspect.

[0047] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the oil pressure control method as described in the first aspect is implemented.

[0048] The beneficial effects of the engine oil pressure control method, device and vehicle of the present invention are as follows: By obtaining the current engine oil temperature and matching it with a plurality of consecutive temperature intervals, the corresponding target temperature interval is determined, and the upper limit engine oil temperature and the lower limit engine oil temperature corresponding to the current engine oil temperature are obtained through this target temperature interval. Through this target temperature interval, the state characteristics of the current engine oil and the possible lubrication requirements of the corresponding engine can be obtained. Thus, the expected engine oil pressure can be accurately calculated according to the working condition characteristics and temperature change situation corresponding to this target temperature interval, making the obtained expected engine oil pressure more in line with the actual situation. And according to the first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature, and the second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature, the expected engine oil pressure of the current engine parameters at the current engine oil temperature is determined through interpolation calculation. The expected engine oil pressure matching the actual required engine oil pressure is accurately obtained through the current engine oil temperature and the current operating condition of the engine. According to the current expected engine oil pressure of the engine, through the control algorithm, the accurate control duty ratio of the oil pump can be obtained, and the oil pump is controlled through the oil pump control duty ratio, so that the oil pump can output the engine oil pressure meeting the engine requirements, thereby meeting the lubrication requirements of the engine. At the same time, when the engine oil temperature, engine speed and engine expected torque change, the determined expected engine oil pressure changes accordingly, and further the oil pump control duty ratio determined according to the expected engine oil pressure also changes adaptively. Therefore, controlling the oil pump according to the oil pump control duty ratio can make the engine oil pressure output by the oil pump respond in time to the change of the engine operating state, avoid risks such as insufficient lubrication and oil leakage caused by the change of the engine operating state, improve the quality and effect of lubrication, ensure the efficient operation of the engine, and extend the service life of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic flow chart of an engine oil pressure control method according to an embodiment of the present invention;

[0050] Figure 2 It is a schematic structural diagram of a motor of a dual-motor hybrid system according to an embodiment of the present invention;

[0051] Figure 3 It is a schematic structural diagram of an engine oil pressure control device according to an embodiment of the present invention;

[0052] Figure 4 It is a schematic structural diagram of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0053] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of specific embodiments of the present invention with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Instead, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the scope of protection of the present invention.

[0054] It should be understood that the various steps described in the method embodiments of the present invention can be executed in different orders and / or executed in parallel. In addition, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this regard.

[0055] As used herein, the term "comprising" and its variations are open-ended, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish different devices, modules, or units, and are not used to limit the order of functions performed by these devices, modules, or units or their interdependent relationships.

[0056] It should be noted that the modifications of "one" and "plural" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless clearly stated otherwise in the context, it should be understood as "one or more".

[0057] The names of the messages or information exchanged between multiple devices in the embodiments of the present invention are only for illustrative purposes and are not used to limit the scope of these messages or information.

[0058] In the related art, the control of oil pressure is crucial for the safety and reliability of engine operation. For example, in a dual-motor hybrid vehicle system, there are usually three modes: pure electric mode, series mode, and parallel mode. In the pure electric mode, the vehicle relies only on the motor for power, and the battery supplies power to the motor to drive the vehicle, while the engine does not operate. In the series mode, the engine does not directly drive the wheels. The mechanical energy generated by the engine is converted into electrical energy through a generator, and then the electrical energy is supplied to the motor to drive the vehicle. If the battery power is insufficient, the engine can also charge the battery. In the parallel mode, the engine and the motor can simultaneously provide power for the vehicle. The engine directly drives the wheels through mechanical transmission, and the motor also provides additional power assistance. As Figure 2 shown, they are respectively the schematic structural diagrams of the engine working in the series mode and the parallel mode. In the series mode, as shown by the arrows in the figure, the engine ENG drives the wheels through the second power output point P2. In the series mode, the clutch C0 is not engaged, and the engine charges the battery through the first power output point P1, and P2 drives the wheels. In the parallel mode, as shown by the arrows in the figure, the engine directly drives the wheels through the first power output point P1, and the clutch C0 is engaged. In the parallel mode and the series mode, since the oil plays an important role in lubrication and cooling during the entire operation of the ENG, when the oil pressure is insufficient, it may cause the ENG to not obtain sufficient oil for lubrication, thus affecting the lubrication effect, and may cause irreversible damage to the ENG. For example, scratches on the relative moving parts caused by an increase in the friction coefficient and a sharp rise in the local temperature, etc. When there is a fault in the oil pressure, the driver must be notified to stop the machine immediately to avoid greater damage.

[0059] Aiming at the problems existing in the above-mentioned related art, this embodiment provides an oil pressure control method, device and vehicle, which can be applied to vehicles with engines such as fuel vehicles and hybrid vehicles.

[0060] As Figure 1 shown, an oil pressure control method provided by an embodiment of the present invention includes:

[0061] S100, determining a target temperature range corresponding to the current engine oil temperature obtained in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit oil temperature and a lower limit oil temperature.

[0062] Specifically, when the engine is at different engine oil temperatures, the characteristics of the engine oil inside it, such as viscosity, will change, and the pressure requirements for lubrication are also different. Match the current engine oil temperature in the engine with a plurality of preset consecutive temperature ranges to obtain the target temperature range corresponding to the current engine oil temperature. Among them, the plurality of preset consecutive temperature ranges can include a plurality of consecutive temperature nodes, that is, the upper limit temperature and the lower limit temperature of each temperature range. These temperature nodes can be obtained through experimental tests. Thus, a plurality of consecutive temperature ranges are generated through the consecutive temperature nodes, and then the current engine oil temperature is compared with each temperature range to determine the temperature range to which the current engine oil temperature belongs, that is, the target temperature range. Through the upper limit temperature and the lower limit temperature of this target temperature range, the upper limit engine oil temperature and the lower limit engine oil temperature corresponding to the current engine oil temperature are obtained.

[0063] For example, according to the experimental test results, set 6 interval temperature points as follows: T 1 is 0 °C, T 2 is 15 °C, T 3 is 100 °C, T 4 is 120 °C, T 5 is 140 °C, T 6 is 160 °C. Thus, the corresponding consecutive temperature ranges can be obtained as follows: the first temperature range is from 0 °C to 15 °C, the second temperature range is from 15 °C to 100 °C, the third temperature range is from 100 °C to 120 °C, the fourth temperature range is from 120 °C to 140 °C, and the fifth temperature range is from 140 °C to 160 °C. Therefore, when the current engine oil temperature is 110 °C, the corresponding target temperature range can be obtained as the third temperature range from 100 °C to 120 °C, and 120 °C is determined as the upper limit engine oil temperature corresponding to the current engine oil temperature, and 100 °C is determined as the lower limit engine oil temperature corresponding to the current engine oil temperature. It should be noted that the first two interval temperature points are also set according to the starting state of the engine. When the engine is in a cold start state, first, according to the experimental results, set the latter four interval temperature points as: T 3 , T 4 , T 5 , T 6 . If the current engine oil temperature is relatively high, that is, the current engine oil temperature exceeds the temperature calibration value in the normal cold start state, and the oil pressure module finds an error and needs to reset the controller, then it is necessary to test the oil pressure control situation at a lower temperature to obtain the corresponding first 2 interval temperature points. These two temperature range points can obtain the temperature range corresponding to the engine oil temperature in the cold start state. Through experiments, it can be obtained that the first two interval temperature points in the cold start state are: T 1 , T 2 .

[0064] S200, perform interpolation calculation based on the first oil pressure corresponding to the current parameters of the engine at the upper limit oil temperature and the second oil pressure corresponding to the current parameters of the engine at the lower limit oil temperature to determine the expected oil pressure corresponding to the current parameters of the engine at the current oil temperature, where the current parameters of the engine include the current speed and the current desired torque of the engine.

[0065] Specifically, the oil pressure in the engine is closely related to the oil temperature, engine speed, and engine torque. When the engine speed is relatively high, the reciprocating movement of the piston becomes faster, and the friction against the cylinder wall becomes larger. Therefore, a greater oil pressure is required to provide more oil to increase the lubrication effect and achieve the effect of protecting the piston. Similarly, when the indicated torque increases, the average pressure borne by the piston becomes larger, correspondingly increasing the friction between the piston and the cylinder wall. Therefore, to increase the lubrication effect, a greater oil pressure is also required to provide more oil to achieve the effect of protecting the piston. In addition, the oil viscosity decreases sharply with the increase in temperature. Therefore, when the temperature rises, a higher oil pressure is also required to provide more oil to ensure the lubrication effect of the engine. Therefore, even at the same oil temperature, as the operating state of the engine changes, the oil pressure will also change accordingly, so as to adjust the oil pressure to meet the requirements of the engine for lubrication effect under different operating states.

[0066] Specifically, through experimental tests, the corresponding relationships between different operating states of the engine and the oil pressure at the upper limit oil temperature and the corresponding relationships between different operating states and the oil pressure at the lower limit oil temperature can be obtained respectively. Thus, according to the current operating state of the engine, that is, the current parameters of the engine, the first oil pressure corresponding to the upper limit oil temperature and the second oil pressure corresponding to the lower limit oil temperature can be determined respectively. Furthermore, interpolation calculation can be performed based on the first oil pressure and the second oil pressure to determine the expected oil pressure corresponding to the current parameters of the engine at the current oil temperature. Thus, through this expected oil pressure, it can be ensured that the oil pressure can be adjusted as the operating state of the engine changes, so that the oil pressure can meet the requirements of the engine operating state for the oil pressure and lubrication effect.

[0067] Exemplarily, the currently obtained oil temperature T is 110 degrees, and the corresponding target temperature range is 100°C to 120°C, so as to obtain the upper limit oil temperature T a of 120°C, and the lower limit oil temperature T b of 100°C. Thus, according to the current speed and the current desired torque of the engine, the first oil pressure P a corresponding to the upper limit oil temperature T 1 and the second oil pressure P b corresponding to the lower limit oil temperature T 2, and it can be approximately linearly changed within the target temperature range. Therefore, the temperature and pressure change process within the temperature range can be approximately represented by a straight line. Among them, (T b , P 2 ) and (T a , P 1 ) can be used as two points on this straight line. Thus, according to the current engine oil temperature T, as well as the corresponding lower limit engine oil temperature T 3 , upper limit engine oil temperature T 4 , first engine oil pressure P 1 and second engine oil pressure P 2 , the expected engine oil pressure can be obtained through interpolation calculation.

[0068] Exemplarily, the expected engine oil pressure satisfies:

[0069] Or

[0070]

[0071] Among them, P is the expected engine oil pressure, P 1 is the first engine oil pressure, P 2 is the second engine oil pressure, T a is the lower limit engine oil temperature, T b is the upper limit engine oil temperature, and T is the current engine oil temperature.

[0072] It should be noted that the expected engine oil pressure may not be fully applicable to the actual situation after a safety failure, and there may be risks of being too high or too low. If the expected pressure is too high, it may exceed the pressure range that the oil pump, filter, oil passage, and each lubricating part of the engine can withstand, resulting in component damage, such as causing the filter element to rupture and leakage at the oil passage seal; while if the expected pressure is too low, it cannot meet the lubrication and cooling requirements of the key components of the engine, and it is easy to cause problems such as increased wear and overheating. Therefore, it is necessary to limit it to ensure that the engine oil pressure is within a relatively reasonable and safe range, that is, the upper limit of the output expected engine oil pressure and the lower limit of the expected engine oil pressure.

[0073] Specifically, the upper limit of the expected engine oil pressure satisfies:

[0074] P max = max(P old + ts × df, P in );

[0075] The lower limit of the expected engine oil pressure satisfies:

[0076] P min = min(P old + ts × dr, P in );

[0077] Among them, P max is the upper limit of the expected engine oil pressure, P min is the lower limit of the expected engine oil pressure, P old is the expected engine oil pressure in the previous sampling period, ts is the set sampling period, for example, ts = 0.01 s, df is the allowable engine oil pressure drop efficiency of the preset expected engine oil pressure, dr is the allowable engine oil pressure rise efficiency of the preset expected engine oil pressure, both df and dr can be measured through experiments, and P in is the input expected engine oil pressure.

[0078] Moreover, when the engine changes from a high-load condition to a low-load condition, the expected engine oil pressure at this time will decrease as the load decreases. However, in order to maintain the oil supply volume and lubrication effect of the oil pump, it is necessary to keep for a certain period of time before allowing the engine oil pressure to decrease step by step. The maintained state can be determined by the engine speed and torque, and when changing from the maintained state to the non-maintained state, a certain delay time is also required, and this time can be determined by the torque.

[0079] Exemplarily, the delay coefficient is obtained by looking up the delay coefficient table according to the current engine speed and the current expected torque of the engine. When the coefficient is greater than or equal to 100, the delay time is 2 s, which is the maintained state. When it is less than or equal to 0, it is the non-maintained state.

[0080] Table 1 is the delay coefficient table:

[0081] Table 1

[0082] Torque / Rotational Speed 1300 r / min 1399 r / min 1400 r / min 1749 r / min 1750 r / min 100 N·m 0 0 0 0 0 101 N·m 100 100 100 100 100 174 N·m 100 100 100 100 100 179 N·m 100 100 100 100 100 180 N·m 100 100 100 100 100 200 N·m 100 100 100 100 100

[0083] S300, determine the oil pump control duty ratio according to the expected engine oil pressure through a control algorithm, and control the oil pump according to the oil pump control duty ratio.

[0084] Specifically, in the lubrication system of the engine, the duty cycle is the ratio of the energized time within a pulse cycle to the total time, and is typically used in Pulse Width Modulation (PWM) technology to control the motor of the oil pump. The feedforward control duty cycle is calculated based on the desired oil pressure and the current operating parameters of the engine. According to the desired oil pressure and the current actual oil pressure, the closed-loop control duty cycle is calculated through a PID controller, where the closed-loop control duty cycle includes the proportional duty cycle, the derivative duty cycle, and the integral duty cycle. At the same time, in order to improve the control accuracy, the duty cycle compensation amount can be further calculated. Finally, the feedforward control duty cycle and the closed-loop control duty cycle are added together to obtain the oil pump control duty cycle, and the oil pump is controlled through the oil pump control duty cycle, that is, the electrical signal of the motor in the oil pump is controlled through the oil pump control duty cycle, so as to adjust the oil pressure output by the oil pump by controlling the motor of the oil pump. Among them, the larger the duty cycle, the longer the energized time of the motor within a pulse cycle, and the faster its speed. Since the oil pump is driven by the motor, the change in the motor speed will change the working state of the oil pump, and thus change the oil pressure. When the speed is fast, the amount of oil delivered by the oil pump per unit time increases and the flow rate accelerates, resulting in an increase in oil pressure; conversely, when the speed is slow, the oil pressure decreases.

[0085] At the same time, since both the oil pump and the motor have working limits, therefore, according to the actual parameter information of the oil pump and the motor therein, through different engine speeds and oil temperatures, combined with the actual parameter information of the oil pump and the motor, the corresponding upper limit duty cycle table and lower limit duty cycle table can be formulated. According to the current oil temperature and the engine speed, the corresponding oil pump duty cycle upper limit and oil pump duty cycle lower limit can be obtained through the upper limit duty cycle relationship and the lower limit duty cycle relationship.

[0086] Table 2 is the lower limit duty cycle relationship table:

[0087] Table 2

[0088] Temperature / Rotational Speed 0 r / min 700 r / min 100 r / min 1500 r / min 2000 r / min 2500 r / min -20℃ 0 0 0 0 0 0 -10℃ 0 0 0 0 0 0 0℃ 0 0 0 0 0 0 20℃ 0 0 0 0 0 0 40℃ 0 0 0 0 0 0

[0089] Table 3 is the upper limit duty cycle relationship table:

[0090] Table 3

[0091]

[0092]

[0093] Furthermore, to improve the control accuracy, necessary corrections can also be made to the duty cycles calculated by feedforward control and PID control. First, a pulse signal generator can be set up to simulate the duty cycle to test the oil pump. The influence of variable valve timing (VVT) control on the duty cycle also needs to be considered. If the oil pump model is low-side drive, the inverse of the duty cycle needs to be calculated, that is, obtained by subtracting the duty cycle from 100. The influence of the temperature of the solenoid coil on the duty cycle correction also needs to be considered. The temperature correction coefficient can be obtained by looking up the temperature correction coefficient table according to the oil temperature.

[0094] Table 4 is the temperature correction coefficient table:

[0095] Table 4

[0096] Temperature -20℃ -10℃ 0℃ 20℃ 40℃ 60℃ 100℃ 120℃ 140℃ Temperature Correction Factor 0.9 1 1 1 1 1 1 1 0.9

[0097] At the same time, the influence of the system voltage on the duty cycle correction also needs to be considered. The voltage correction coefficient can be obtained by looking up the voltage correction coefficient table according to the voltage.

[0098] Table 5 is the voltage correction coefficient table:

[0099] Table 5

[0100] Voltage 6V 8V 10V 12V 14V 16V 18V Voltage Correction Factor 0.9 1 1 1 1 0.9 0.9

[0101] By looking up the corresponding temperature correction coefficient according to the current oil temperature and Table 4, and looking up the corresponding pressure correction coefficient according to the system voltage and Table 5, the product of the duty cycle of the oil pump control obtained by the control algorithm, the temperature correction coefficient, and the voltage correction coefficient can be determined as the final duty cycle of the oil pump control.

[0102] Moreover, at the engine idle state, the oil pressure is relatively low. When the oil temperature is high, the expected idle value can be appropriately increased. When the oil temperature is low, the expected idle value can also be appropriately decreased. When the engine is in the running state and the oil pressure is less than a certain value, after a specific time, the adjustment state of the idle value can be obtained by looking up the idle state table according to the current oil temperature. When the oil pressure reaches the normal state, the idle value is set to 0, and the idle value of the engine is not adjusted.

[0103] Table 6 is the idle state table for the normal state of the oil pressure:

[0104] Table 6

[0105] Engine Oil Temperature 0℃ 1℃ 2℃ 3℃ 4℃ 5℃ 6℃ 7℃ Idle State 0 0 0 0 0 0 0 0

[0106] Finally, the expected idle value can also be restricted. The upper limit of the idle value satisfies:

[0107] n max =max(nold +ts×nf, n in );

[0108] The lower limit of the idle value satisfies:

[0109] n min = min(n old +ts×nr, n in );

[0110] Wherein, n max is the upper limit of the idle value, n min is the lower limit of the idle value, n old is the expected idle value of the previous sampling period, ts is the set sampling period, for example ts = 0.01 s, nf is the allowable idle value decrease efficiency of the preset expected engine idle value, nr is the allowable idle value increase efficiency of the preset expected idle value, both nf and nr can be measured through experiments, n in is the input expected idle value.

[0111] Of course, if the idle value calculated based on the current engine oil temperature is greater than the expected idle value, and the actual engine oil pressure is within the normal range, then there is no need to limit this idle value, and the expected idle value can be obtained by looking up the expected idle value table according to the engine coolant temperature and the ambient atmospheric pressure.

[0112] Table 7 is the expected idle value table:

[0113] Table 7

[0114]

[0115]

[0116] It should be noted that 1) when the engine is in the shutdown state; 2) the engine oil pressure detected within the preset startup time is less than the preset startup pressure; 3) the current engine oil temperature is less than the preset temperature, the current actual engine oil pressure is less than the preset pressure, and the increase amount of the current expected engine oil pressure is greater than the preset increase threshold; if any one or more of the above three situations occur, at this time, if the previous parameters and the data accumulated inside the controller (such as the cumulative value of the integral term) are directly used, it may not be possible to effectively control the system accurately according to the current actual situation. By resetting the controller, the parameters can be restored to the initial default values, the cumulative value of the integral term can be cleared, etc., which can enable the controller to reasonably regulate starting from scratch based on the current actual working conditions, quickly adapt to the system state during the startup phase, and make the system operate stably towards the set target value.

[0117] In this embodiment, by obtaining the current engine oil temperature and matching it with a plurality of consecutive temperature ranges, the corresponding target temperature range is determined, and the upper limit engine oil temperature and the lower limit engine oil temperature corresponding to the current engine oil temperature are obtained through the target temperature range. Through the target temperature range, the state characteristics of the current engine oil and the possible lubrication requirements of the corresponding engine can be obtained. Thus, the expected engine oil pressure can be accurately calculated according to the operating characteristics and temperature change conditions of the target temperature range, making the obtained expected engine oil pressure more in line with the actual situation. And according to the first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature and the second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature, the expected engine oil pressure of the current engine parameters at the current engine oil temperature is determined by interpolation calculation. The expected engine oil pressure matching the actual required engine oil pressure is accurately obtained through the current engine oil temperature and the current operating condition of the engine. According to the current expected engine oil pressure of the engine, the accurate control duty ratio of the oil pump can be obtained through a control algorithm. The oil pump is controlled by the oil pump control duty ratio, so that the oil pump can output the engine oil pressure meeting the engine requirements, thereby meeting the lubrication requirements of the engine. At the same time, when the engine oil temperature, engine speed, and engine expected torque change, the determined expected engine oil pressure changes accordingly. Furthermore, the oil pump control duty ratio determined according to the expected engine oil pressure also changes adaptively. Therefore, controlling the oil pump according to the oil pump control duty ratio can enable the engine oil pressure output by the oil pump to respond in a timely manner to the changes in the operating state of the engine, avoiding risks such as insufficient lubrication and oil leakage caused by changes in the engine operating state, improving the quality and effect of lubrication, ensuring the efficient operation of the engine, and extending the engine life.

[0118] Optionally, before performing the interpolation calculation based on the first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature and the second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature, the engine oil pressure control method further includes:

[0119] Determining the first engine oil pressure matching relationship corresponding to the upper limit engine oil temperature and the second engine oil pressure matching relationship corresponding to the lower limit engine oil temperature respectively;

[0120] Determining the first engine oil pressure according to the current engine parameters in the first engine oil pressure matching relationship, and determining the second engine oil pressure according to the current engine parameters in the second engine oil pressure matching relationship, where the first engine oil pressure matching relationship and the second engine oil pressure matching relationship respectively include the corresponding relationship between the current engine parameters and the engine oil pressure at the corresponding temperature.

[0121] Specifically, through experimental tests, the oil pressure matching relationships corresponding to the upper and lower limit temperatures in each temperature range can be obtained in advance, so as to determine the oil pressure matching relationship corresponding to the upper limit oil temperature as the first oil pressure matching relationship, and the oil pressure matching relationship corresponding to the lower limit oil pressure as the second oil pressure matching relationship. For example, the 5 set increasing temperature ranges respectively include 6 gradually increasing interval temperature points, namely T 1 is 0 °C, T 2 is 15 °C, T 3 is 100 °C, T 4 is 120 °C, T 5 is 140 °C, T 6 is 160 °C. According to each interval temperature point, the respective corresponding oil pressure matching relationships are obtained through experimental tests as follows:

[0122] Table 8 is the oil pressure matching relationship table corresponding to T 1 :

[0123] Table 8

[0124]

[0125] Table 9 is the oil pressure matching relationship table corresponding to T 2 :

[0126] Table 9

[0127]

[0128] Table 10 is the oil pressure matching relationship table corresponding to T 3 :

[0129] Table 10

[0130]

[0131] Table 11 is the oil pressure matching relationship table corresponding to T 4 :

[0132] Table 11

[0133]

[0134] Table 12 is the oil pressure matching relationship table corresponding to T 5 :

[0135] Table 12

[0136]

[0137] Table 13 is the oil pressure matching relationship table corresponding to T 6 :

[0138] Table 13

[0139]

[0140] Therefore, when the current engine oil temperature is 110 degrees, the current engine oil temperature is within the temperature range determined by T3 and T4, that is, the lower limit engine oil temperature is 100 °C and the upper limit engine oil temperature is 120 °C. Then, the engine oil pressure matching relationship corresponding to 120 °C is determined as the first engine oil pressure matching relationship, and the engine oil pressure matching relationship corresponding to 100 °C is determined as the second engine oil pressure matching relationship. When the current engine parameters include the current engine speed of 1050 r / min and the current desired torque of 100 N·m, through the first engine oil pressure matching relationship corresponding to 120 °C, the first engine oil pressure P 1 corresponding to the upper limit engine oil temperature is 400 kPa, and through the second engine oil pressure matching relationship corresponding to 100 °C, the second engine oil pressure P 2 corresponding to the lower limit engine oil temperature is 180 kPa.

[0141] It should be noted that if the current engine oil temperature is lower than the temperature of the first interval temperature point, that is, the temperature of the lowest interval temperature point, then the engine oil pressure corresponding to the lowest interval temperature point is directly assigned to the current desired engine oil pressure; if the current temperature is higher than the temperature of the sixth interval temperature point, that is, higher than the temperature of the highest interval temperature point, then the engine oil pressure corresponding to the highest interval temperature point is directly assigned to the current desired engine oil pressure.

[0142] In this alternative embodiment, in combination with the current operating state of the engine, the corresponding first engine oil pressure and second engine oil pressure are determined respectively through the upper limit engine oil temperature and the lower limit engine oil temperature. Thus, through the first engine oil pressure and the second engine oil pressure, the desired engine oil pressure of the engine can be limited within a reasonable range, avoiding a large deviation in the desired engine oil pressure, ensuring that the obtained desired engine oil pressure matches the engine oil pressure required by the actual operating state of the engine, thereby improving the accuracy of the finally obtained desired engine oil pressure.

[0143] Optionally, the step of interpolating and calculating the desired engine oil pressure corresponding to the current engine oil temperature according to the first engine oil pressure corresponding to the current engine parameters at the upper limit engine oil temperature and the second engine oil pressure corresponding to the current engine parameters at the lower limit engine oil temperature includes:

[0144] Determining the ratio of the difference between the current engine oil temperature and the lower limit engine oil temperature to the temperature width of the temperature range to obtain a first pressure proportionality factor; determining the ratio of the difference between the upper limit engine oil temperature and the current engine oil temperature to the temperature width to obtain a second pressure proportionality factor; wherein, the temperature width is the difference between the upper limit engine oil temperature and the lower limit engine oil temperature;

[0145] Add the product of the first engine oil pressure and the first pressure ratio factor and the product of the second engine oil pressure and the second pressure ratio factor to obtain the desired engine oil pressure.

[0146] Specifically, according to the difference between the upper limit engine oil temperature and the lower limit engine oil temperature, determine the temperature width of the target temperature range, and thus determine the distance between the current engine oil temperature and the lower limit engine oil temperature through the difference between the current engine oil temperature and the lower limit engine oil temperature. Divide this difference by the temperature width of the target temperature range to obtain the first pressure ratio factor corresponding to the first engine oil pressure. Similarly, divide the difference between the upper limit engine oil temperature and the current engine oil temperature by the temperature width to obtain the second pressure ratio factor corresponding to the second engine oil pressure. Then, through the product of the first engine oil pressure and the first ratio factor, obtain the contribution value of the first engine oil pressure to the desired engine oil pressure. Through the product of the second engine oil pressure and the second ratio factor, obtain the contribution value of the second engine oil pressure to the desired engine oil pressure. Finally, add the contribution values of the first engine oil pressure and the second engine oil pressure to the desired engine oil pressure to obtain the desired engine oil pressure corresponding to the current operating state of the engine at the current engine oil temperature.

[0147] Exemplarily, the desired engine oil pressure satisfies:

[0148]

[0149] where P is the desired engine oil pressure, P a is the second engine oil pressure, P b is the first engine oil pressure, T a is the lower limit engine oil temperature, T b is the upper limit engine oil temperature, and T is the current engine oil temperature.

[0150] In this alternative embodiment, an accurate desired engine oil pressure is obtained through interpolation calculation, which can more accurately determine the engine oil pressure most suitable for the current working conditions according to the actual operating parameters of the current engine and the corresponding engine oil temperature, so as to ensure that the engine can obtain good lubrication and cooling effects under various working conditions, and reduce wear and failures.

[0151] It should be noted that the desired engine oil pressure can be further restricted according to the state of the engine: 1) In the cold start stage, at this time the viscosity of the engine oil is small. In order to reduce the engine oil resistance and enable the engine to start normally, less engine oil needs to be provided to the engine. Therefore, a maximum limit needs to be imposed on the desired engine oil pressure, and this limit value can be obtained from the cold start engine oil pressure upper limit table through the current engine oil temperature and the time after starting.

[0152] Table 14 is the cold start engine oil pressure upper limit table:

[0153] Table 14

[0154] Engine Oil Temperature / Time 2s 2.1s 10s 15s 20s 25s 30s 50s -20℃ 400 180 180 180 180 180 180 180 0℃ 400 180 180 180 180 180 180 180 20℃ 400 180 180 180 180 180 180 180 50℃ 400 180 180 180 180 180 180 180

[0155] When the intake manifold pressure is low, in order to reduce the oil resistance, a lower oil pressure is also required. Therefore, it is necessary to limit the maximum value of the desired oil pressure, which can be obtained by looking up the intake manifold oil pressure upper limit table according to the engine speed and the intake manifold partial pressure.

[0156] Table 15 is the intake manifold oil pressure upper limit table:

[0157] Table 15

[0158]

[0159] When the atmospheric pressure is less than a certain value and the oil pressure monitoring module determines that the controller needs to be reset, it is necessary to consider the influence of the atmospheric pressure on the desired oil pressure, and it is also necessary to limit the maximum value of the desired oil pressure, which is obtained by looking up the oil pressure upper limit table after controller reset according to the oil temperature and the engine coolant temperature; otherwise, the influence of the atmospheric pressure on the desired oil pressure is not considered.

[0160] Table 16 is the oil pressure upper limit table after controller reset:

[0161] Table 16

[0162] Engine Oil Temperature / Coolant Temperature -40℃ -20℃ -10℃ 0℃ 50℃ 80℃ 100℃ -40℃ 400 180 180 180 180 180 180 -10℃ 400 180 180 180 180 180 180 0℃ 400 180 180 180 180 180 180 50℃ 400 180 180 180 180 180 180

[0163] When the piston cooling is turned off, in order to increase the lubrication effect, it is necessary to appropriately increase the desired oil pressure. When the oil pressure is greater than a certain limit value, it indicates that there is enough oil and the piston does not need to be cooled; on the contrary, when the oil pressure is less than a certain limit value, it indicates that there is less oil and the cooling effect on the piston will become weaker. To solve this problem, it is necessary to increase the oil pressure to obtain enough oil. The specific logic is as follows: when the basic desired pressure is less than the pressure threshold (300 kPa) for piston cooling off, start timing for this working condition. When the time is greater than the piston cooling stop time, delay for a certain time, and the desired pressure within this time is set to the calibrated value (400 kPa); on the contrary, when the basic desired pressure is greater than the pressure threshold for piston cooling off, the desired pressure value is immediately set to the calibrated value (400 kPa) and maintained for a certain time, and then the desired pressure value returns to the basic desired pressure value.

[0164] Optionally, determining the duty ratio of the oil pump control according to the desired oil pressure includes:

[0165] Determine the target oil pressure range corresponding to the desired oil pressure among a plurality of consecutive oil pressure ranges, and perform interpolation calculation based on the first duty ratio corresponding to the upper limit oil pressure of the target oil pressure range at the current speed and the second duty ratio corresponding to the lower limit oil pressure of the target oil pressure range at the current speed to determine the feedforward control duty ratio corresponding to the current speed at the desired oil pressure;

[0166] Determine the closed-loop control duty ratio according to the acquired current actual oil pressure and the desired oil pressure;

[0167] Add the feedforward control duty ratio and the closed-loop control duty ratio to obtain the oil pump control duty ratio.

[0168] Specifically, compare the desired oil pressure with a plurality of consecutive preset oil pressure ranges to obtain the target oil pressure range corresponding to the desired oil pressure, and determine the upper limit oil pressure and the lower limit oil pressure corresponding to the desired oil pressure according to this target oil pressure range, so as to determine the first duty ratio corresponding to the current speed according to the upper limit oil pressure, and determine the second duty ratio corresponding to the current speed according to the lower limit oil pressure. Through the desired oil pressure, the upper limit oil pressure, the lower limit oil pressure, the first duty ratio and the second duty ratio, perform interpolation calculation to obtain the feedforward control duty ratio corresponding to the current engine speed at the desired oil pressure. When regulating the oil pressure, the feedforward control duty ratio can adjust the power supply situation of the oil pump motor in advance, that is, according to the desired oil pressure, based on data such as the engine speed and torque, the oil pump is controlled in advance by adjusting the feedforward control duty ratio, so that the oil pressure output by the oil pump can quickly and accurately reach the desired oil pressure, thereby improving the control accuracy of the oil pressure in the lubrication system. Through stable and accurate oil pressure control, the oil pressure can be dynamically controlled according to the requirements of different operating states of the engine, ensuring the lubrication effect of the engine and contributing to the stable and efficient operation of the engine.

[0169] Exemplarily, the feedforward control duty ratio satisfies:

[0170] Or

[0171]

[0172] Where D is the feedforward control duty ratio, D 2 is the second duty ratio, D 1 is the first duty ratio, P b is the upper limit oil pressure, P a is the lower limit oil pressure, and T is the desired oil pressure.

[0173] It should be noted that if the current desired oil pressure is less than the pressure point P of the first interval 1 , that is, the minimum interval pressure point, then the duty ratio corresponding to the minimum interval pressure point is directly assigned to the current feedforward control duty ratio; if the current desired oil pressure is higher than the pressure point of the fourth interval, that is, the maximum interval pressure point, then the duty ratio corresponding to the maximum interval pressure point is directly assigned to the current feedforward control duty ratio. At the same time, to prevent a sudden drop in oil pressure, when the calculated feedforward control duty ratio decreases, it needs to remain unchanged for a certain period of time (2 s).

[0174] Furthermore, the currently obtained actual oil pressure is used to calculate the closed-loop control duty ratio of the oil pump control according to the deviation between the current actual oil pressure and the desired oil pressure. The oil pump is controlled by the closed-loop control duty ratio. According to the deviation between the current actual oil pressure and the desired oil pressure, the control duty ratio of the oil pump is adjusted, so as to correct the deviation generated, and make the actually output oil pressure closer to the desired oil pressure. Finally, the feedforward control duty ratio and the closed-loop control duty ratio are added together to obtain the oil pump control duty ratio of the oil pump. By controlling the oil pump with the oil pump control duty ratio, the oil pressure output by the oil pump can better adapt to the oil pressure requirements of different operating states of the engine, ensure that the oil is stably delivered to each lubricating part of the engine, avoid phenomena such as increased wear of engine components and abnormal operation caused by unstable oil supply, ensure the stable operation of the engine lubrication system, improve the lubrication effect on the engine, and extend the service life of the engine.

[0175] In this optional embodiment, the duty ratio of the oil pump is adjusted in advance through the feedforward control duty ratio, so that the oil pressure can adapt in advance, ensuring that each lubricating part can obtain sufficient oil in time, and enabling the engine to smoothly transition to the corresponding state or meet the lubrication requirements of special components. And the closed-loop control duty ratio can monitor and adjust the duty ratio in real time according to the change of the oil pressure demand, maintaining the oil pressure near the desired pressure value, ensuring long-term stable lubrication of the engine. Through the cooperation of the feedforward control duty ratio and the closed-loop control duty ratio, the response speed and accuracy can be improved, enabling the oil pressure to quickly and accurately reach the ideal oil pressure. At the same time, the stability and reliability of the lubrication system are enhanced. The feedforward reduces the complexity of the closed-loop regulation, and the closed-loop ensures long-term stability, guaranteeing the lubrication effect of the engine, reducing the risk of engine failure, and ensuring the efficient and reliable operation of the engine.

[0176] Optionally, before performing the interpolation calculation according to the first duty ratio corresponding to the upper limit oil pressure of the target oil pressure interval at the current speed and the second duty ratio corresponding to the lower limit oil pressure of the target oil pressure interval at the current speed, the oil pressure control method further includes:

[0177] Determine the first duty ratio matching relationship corresponding to the upper limit oil pressure and the second duty ratio matching relationship corresponding to the lower limit oil pressure respectively;

[0178] Determine the first duty ratio in the first duty ratio matching relationship according to the current oil temperature and the current rotational speed, and determine the second duty ratio in the second duty ratio matching relationship according to the current oil temperature and the current rotational speed, wherein the first duty ratio matching relationship and the second duty ratio matching relationship include the corresponding relationships between the current oil temperature, the current rotational speed and the duty ratio under the corresponding oil pressures.

[0179] Specifically, through experimental tests, the first duty ratio matching relationship corresponding to the upper limit oil pressure and the second duty ratio matching relationship corresponding to the lower limit oil pressure can be obtained, so that the first duty ratio corresponding to the upper limit oil pressure can be determined in the first duty ratio matching relationship according to the current rotational speed of the engine, and the second duty ratio corresponding to the lower limit oil pressure can be determined in the second duty ratio matching relationship. For example, three consecutive oil pressure intervals are set according to the experimental test results, that is, the first oil pressure interval is 399 kPa to 400 kPa, the second oil pressure interval is 400 kPa to 500 kPa, and the third oil pressure interval is 500 kPa to 600 kPa, so that four oil pressure interval nodes can be obtained, that is, P e1 is 399 kPa, P e2 is 400 kPa, P e3 is 500 kPa, P e4 is 600 kPa, and the duty ratio matching relationships corresponding to P e1 、P e2 、P e3 and P e4 are constructed respectively through the experimental test results. Among them, each duty ratio matching relationship includes the corresponding relationship between different combinations of oil temperature and rotational speed and the duty ratio. The duty ratio matching relationship is as follows:

[0180] Table 17 is the duty ratio matching relationship table corresponding to the interval pressure point P e1 :

[0181] Table 17

[0182]

[0183]

[0184] Table 18 is the duty ratio matching relationship table corresponding to the interval pressure point P e2 :

[0185] Table 18

[0186]

[0187] Table 19 shows the duty cycle matching relationship table for the interval pressure point P e3 corresponding to:

[0188] Table 19

[0189]

[0190] Table 20 shows the duty cycle matching relationship table for the interval pressure point P e4 corresponding to:

[0191] Table 20

[0192]

[0193]

[0194] Furthermore, when the desired engine oil pressure is 450 kPa, by comparing with each engine oil pressure interval respectively, it can be known that the desired engine oil pressure is in the second engine oil pressure interval, that is, the second engine oil pressure interval is the target engine oil pressure interval. Therefore, the upper limit P e3 of the target engine oil pressure interval is determined as the upper limit engine oil pressure, which is 500 kPa, and the P e3 corresponding duty cycle matching relationship is determined as the first duty cycle matching relationship. The lower limit P e2 of the target pressure interval is determined as the lower limit engine oil pressure, which is 400 kPa 2 and the P e2 corresponding duty cycle matching relationship is determined as the second duty cycle matching relationship. Thus, according to the current engine oil temperature and the current engine speed, through the first duty cycle matching relationship, the first duty cycle corresponding to the upper limit engine oil pressure under the conditions of the current engine oil temperature and the current engine speed is determined, and through the second duty cycle matching relationship, the second duty cycle corresponding to the lower limit engine oil pressure under the conditions of the current engine oil temperature and the current engine speed is determined.

[0195] In this alternative embodiment, by combining the current engine speed and the current engine oil temperature, the corresponding first duty cycle and second duty cycle are respectively matched through the upper limit engine oil pressure and the lower limit engine oil pressure. Thus, the feedforward duty cycle of the engine can be limited within a reasonable range through the first duty cycle and the second duty cycle, ensuring that the engine oil pump can be accurately controlled through the feedforward duty cycle, so that the engine oil pressure output by the engine oil pump matches the required engine oil pressure, thereby improving the lubrication effect on the engine.

[0196] Optionally, performing interpolation calculation based on a first duty ratio corresponding to an upper oil pressure of the target oil pressure range at the current rotational speed and a second duty ratio corresponding to a lower oil pressure of the target oil pressure range at the current rotational speed to determine a feedforward control duty ratio corresponding to the current rotational speed at the desired oil pressure, includes:

[0197] Determining a ratio between a difference between the desired oil pressure and the lower oil pressure and a pressure width of the oil pressure range to obtain a first duty ratio proportionality factor; determining a ratio between a difference between the upper oil pressure and the current oil pressure and the pressure width to obtain a second duty ratio proportionality factor, where the pressure width is a difference between the upper oil pressure and the lower oil pressure;

[0198] Adding a product of the first duty ratio and the first duty ratio proportionality factor and a product of the second duty ratio and the second duty ratio proportionality factor to obtain the feedforward control duty ratio.

[0199] Specifically, based on a difference between the upper oil pressure and the lower oil pressure of the target oil pressure range, determining the pressure width of the oil pressure range, thereby determining a distance between the desired oil pressure and the lower oil pressure through a difference between the desired oil pressure and the lower oil pressure, and obtaining a first duty ratio proportionality factor corresponding to the desired oil pressure by dividing the difference by the pressure width. Similarly, dividing a difference between the upper oil pressure and the desired oil pressure by the pressure width to obtain a second duty ratio proportionality factor corresponding to the desired oil pressure, then obtaining a contribution value of the first duty ratio to the feedforward control duty ratio through a product of the first duty ratio and the first duty ratio proportionality factor, obtaining a contribution value of the second duty ratio to the feedforward control duty ratio through a product of the second duty ratio and the second duty ratio proportionality factor, and finally adding the contribution values of the first duty ratio and the second duty ratio to the feedforward control duty ratio to obtain an accurate feedforward control duty ratio corresponding to the desired oil pressure.

[0200] Exemplarily, the feedforward control duty ratio satisfies:

[0201]

[0202] where D is the feedforward control duty ratio, D 2 is the second duty ratio, D 1 is the first duty ratio, P a is the lower oil pressure, P b is the upper oil pressure, and T is the desired oil pressure.

[0203] In this optional embodiment, the upper oil pressure and the lower oil pressure corresponding to the desired oil pressure are determined through the target oil pressure range corresponding to the desired oil pressure. Thus, the positional relationship between the desired oil pressure and the upper oil pressure and the lower oil pressure can be judged by comparing the three. Then, according to the first duty ratio matching relationship corresponding to the upper oil pressure and the second duty ratio matching relationship corresponding to the lower oil pressure, the first duty ratio corresponding to the upper oil pressure and the second duty ratio corresponding to the lower oil pressure are determined through the current oil temperature and the engine speed. Thus, an accurate feedforward duty ratio corresponding to the desired oil pressure is calculated through the current oil pressure, the upper oil pressure, the lower oil pressure, the first duty ratio, and the second duty ratio. The oil pump can be controlled in advance through the feedforward duty ratio, ensuring that the oil pressure output by the oil pump can meet the lubrication requirements expected by the engine, and effectively improving the lubrication effect on the engine.

[0204] Optionally, determining the closed-loop control duty ratio according to the obtained current actual oil pressure and the desired oil pressure includes:

[0205] Determining the oil pressure desired deviation as the difference between the desired oil pressure and the desired oil pressure of the previous sampling period obtained, multiplying the ratio of the oil pressure desired deviation to the sampling period by a preset compensation coefficient after filtering to obtain a duty ratio compensation amount;

[0206] Determining the oil pressure actual deviation as the difference between the current actual oil pressure and the actual oil pressure of the previous sampling period obtained, multiplying the ratio of the oil pressure actual deviation to the sampling period by a preset differential coefficient after the filtering to obtain a differential duty ratio;

[0207] Determining the oil pressure current deviation as the difference between the current actual oil pressure and the desired oil pressure, and determining the product of the oil pressure current deviation and a preset proportionality coefficient as the proportional duty ratio;

[0208] Summing the differences between the actual oil pressure and the desired oil pressure corresponding to each sampling period and multiplying by a preset integral coefficient to obtain an initial integral duty ratio, and subtracting the product of a preset duty ratio limit value and a correction coefficient from the initial integral duty ratio to obtain the integral duty ratio;

[0209] Adding the duty ratio compensation amount, the differential duty ratio, the proportional duty ratio, and the integral duty ratio to obtain the closed-loop control duty ratio.

[0210] Specifically, the oil pressure desired deviation is obtained based on the difference between the desired oil pressure and the desired oil pressure in the previous sampling period. Thus, the change amount of the current desired oil pressure can be determined through this oil pressure desired deviation. Then, the oil pressure desired deviation is divided by the sampling period to obtain the change rate of the desired oil pressure. After the obtained change rate is processed by a filtering function, it is multiplied by a preset compensation coefficient to finally obtain the duty cycle compensation amount. Through filtering, the noise interference in the data can be removed, thereby improving the stability and reliability of the data and ensuring the accuracy of the finally obtained duty cycle compensation amount.

[0211] Exemplarily, the duty cycle compensation amount satisfies:

[0212]

[0213] Wherein, X comp is the duty cycle compensation amount, Filt() is the filtering function, P is the desired oil pressure, P old is the desired oil pressure in the previous sampling period, ts is the sampling period, α is the compensation coefficient, and this compensation coefficient can be set according to the deviation between the desired oil pressure and the actual oil pressure, as well as the engine speed and the oil temperature.

[0214] Further, the actual oil pressure in the previous sampling period is obtained. The difference between the current actual oil pressure and the actual oil pressure in the previous sampling period is used as the actual oil pressure deviation. Through this actual oil pressure deviation, the change amount of the actual oil pressure between two sampling periods can be obtained. The ratio of this actual oil pressure deviation to the sampling period gives the change rate of the current actual oil pressure. After the change rate is processed by a filtering function, it is multiplied by a set differential coefficient to obtain the differential duty cycle.

[0215] Exemplarily, the differential duty cycle satisfies

[0216]

[0217] Wherein, X D is the differential duty cycle, Filt() is the filtering function, P′ is the current actual oil pressure, P′ old is the actual oil pressure in the previous sampling period, ts is the sampling period, β is the differential coefficient, and this differential coefficient can be set according to the deviation between the desired oil pressure and the actual oil pressure, as well as the engine speed and the oil temperature.

[0218] Further, the difference between the current actual oil pressure and the desired oil pressure is used as the current deviation of the oil pressure. Through the current deviation of the oil pressure, the difference between the current oil pressure and the desired adjusted oil pressure can be understood, that is, the amount by which the oil pressure needs to be adjusted in the next sampling period. Thus, the proportional duty ratio is obtained by multiplying the current deviation of the oil pressure by a preset proportionality coefficient.

[0219] Exemplarily, the proportional duty ratio satisfies:

[0220] X P =P err *γ;

[0221] Wherein, X P is the proportional duty ratio, P err is the current deviation of the oil pressure, γ is the proportionality coefficient, and the proportionality coefficient can be set according to the engine speed and the oil temperature.

[0222] Further, by subtracting the desired oil pressure from the actual oil pressure corresponding to each sampling period, the deviation between the actual oil pressure and the desired oil pressure corresponding to each sampling period is obtained. The differences between the actual oil pressure and the desired oil pressure for each sampling period are added together to obtain the cumulative deviation amount of the actual oil pressure and the desired oil pressure for all sampling periods. The cumulative deviation amount is multiplied by a preset integral coefficient to obtain the initial integral duty ratio. The initial integral duty ratio is subtracted by the product of a preset duty ratio overrun value and a correction coefficient to obtain the final integral duty ratio.

[0223] Exemplarily, the integral duty ratio satisfies:

[0224]

[0225] Wherein, X I is the integral duty ratio, P i is the difference between the actual oil pressure and the desired oil pressure in the i-th sampling period, δ is the integral coefficient, and the integral coefficient can be set according to the deviation between the desired oil pressure and the actual oil pressure, as well as the engine speed and the oil temperature. X track is the duty ratio overrun value, Z track is the correction coefficient, and N is the number of sampling periods.

[0226] Further, the duty ratio compensation amount, the differential duty ratio, the proportional duty ratio, and the integral duty ratio are added together to obtain the closed-loop control duty ratio for the oil pump control.

[0227] In this alternative embodiment, in the proportional (P) part: the proportional duty cycle can quickly respond to the deviation of the oil pressure, and its adjustment intensity is proportional to the deviation magnitude. This enables the oil pump to rapidly change its operating state according to the deviation between the actual and desired oil pressures, with delicate adjustment, avoiding excessive fluctuations in parameters such as oil pressure, and ensuring the stability of the lubrication system and that the parameters conform to the actual requirements. In the integral (I) part: the integral duty cycle can eliminate the steady-state error. By accumulating and calculating the continuously existing small deviations and then adjusting the duty cycle, the actual output can more precisely reach the set value; it can also improve the control stability, gently change the duty cycle to reduce system fluctuations, which is beneficial for oil supply under long-term stable operating conditions and ensures the stability of oil supply. In the derivative (D) part: the derivative duty cycle can suppress system overshoot. By predicting and adjusting the duty cycle based on the parameter change rate, it avoids over-adjustment, enabling the parameters to smoothly reach the expected value; it can also enhance the system response speed and dynamic performance, enabling the oil pump to timely and precisely adjust its operating state when the operating conditions change frequently, ensuring that the oil supply matches the lubrication effect required by the engine.

[0228] To ensure the stable operation of the engine, it is also necessary to monitor the oil pressure. When monitoring the oil pressure, determining whether there is an abnormality in the oil pressure mainly falls into the following three situations:

[0229] 1) Whether too low oil pressure will cause direct damage to the engine during the engine's operating state. Based on this idea, calculate the boundary value of the minimum oil pressure, and then add factors such as oil temperature, engine speed, and torque that affect the oil pressure boundary value. By comparing the difference between the actual oil pressure value and the boundary value at this time, evaluate whether the oil pressure is too low to cause engine damage.

[0230] 2) Whether there is a large offset in the oil pressure sensor. The monitoring of the offset mainly determines whether the offset exceeds the limit based on the reference sensor. (When the positive offset exceeds the limit, it will cause the actual oil pressure to be too low, then the oil pump needs to be directly turned to the maximum to avoid the situation of too low actual oil pressure; when the negative offset is too large, it will cause the actual oil pressure to be too high, then there may be a false alarm when the oil pressure is low. Therefore, when the offset exceeds the limit, the control of the oil pump directly enters the open-loop control.) Since the reference sensors are the atmospheric pressure sensor and the boost pressure sensor, in order to make the reference sensor and the oil pressure sensor comparable, it is necessary to define the comparable conditions between them. When the offset of the oil pressure sensor is too large, it directly causes errors in the control of the oil pump; therefore, open-loop control needs to be carried out on it.

[0231] 3) Sticking of the oil pressure sensor. After the engine starts running and the oil pump starts working, since the engine operates in an intermittent cycle mode, small fluctuations in oil pressure will occur anyway. Based on this consideration, after it is determined that the engine and the oil pump start working, the oil pressure accuracy of the oil pump is used to determine whether the oil pressure sensor is stuck. When the oil pressure sensor is stuck, the control of the oil pump becomes unreliable; to avoid failure non-reporting and false failure reporting, it is necessary to directly use the maximum pump oil volume to solve this problem.

[0232] Optionally, the control method further includes:

[0233] Monitoring the current actual oil pressure of the engine;

[0234] When the current actual oil pressure exceeds a preset stuck oil pressure range, it is determined that the oil pressure sensor is stuck; and / or,

[0235] Based on the current state of the engine, by comparing the current actual oil pressure with a preset threshold, it is determined whether the current actual oil pressure is abnormal.

[0236] Specifically, after the oil pump starts working, since the engine operates in an intermittent cycle mode, small fluctuations in oil pressure may occur. Therefore, after it is determined that the engine and the oil pump start working, the oil pressure accuracy of the oil pump is used to determine whether the oil pressure sensor is stuck. When the oil pressure sensor is stuck, the control of the oil pump becomes unreliable. To avoid failure non-reporting and false failure reporting, it is necessary to directly use the maximum pump oil volume to solve this problem. To avoid the above situation, it is necessary to monitor whether the oil pressure sensor is stuck. There are two situations where the oil pressure sensor is stuck: 1. Sticking in the high oil pressure section, which may cause the oil pressure controlled by the oil pump to always move towards the low oil pressure, resulting in too low an actual oil pressure value and damage to the engine; 2. Sticking in the low oil pressure section, which may cause the oil pressure pump to always move towards the high oil pressure, resulting in an increase in the power required by the oil pump and wasting energy.

[0237] Furthermore, when the detected actual oil pressure exceeds the preset stuck oil pressure range, it is determined that the oil pressure sensor is stuck. The stuck oil pressure range includes the preset upper limit and lower limit of the stuck pressure. After starting the monitoring of the oil pressure stuck, it is judged whether the change of the oil pressure is less than the lower limit of the stuck pressure within a period of time. If it is less than the lower limit of the stuck pressure, it is judged that a stuck occurs; and when the oil pressure is greater than the upper limit of the stuck pressure and disappears inside within a period of time, it can also be judged that the oil pressure sensor is stuck. For the smoothness of diagnosis and to avoid the occasional jump of the diagnosis value, two delays are used, namely the rising edge delay and the falling edge delay. When the current actual oil pressure is less than the lower limit of the stuck pressure or greater than the upper limit of the stuck pressure, it is considered that the current actual oil pressure exceeds the set stuck oil pressure range, thereby determining that the oil pressure sensor is faulty. It is also possible not to set the delay according to the actual situation and directly judge whether it is stuck based on the comparison result.

[0238] At the same time, during the operation of the engine, the oil pressure will be adjusted according to the change of the engine operation state to meet the requirements of the oil pressure and lubrication effect under different engine operation states. Therefore, under different engine operation states, it is also necessary to perform dynamic monitoring along with the fluctuation of the oil pressure, that is, to set the preset threshold corresponding to the oil pressure in each state according to different engine operation states, compare the current actual oil pressure with the preset threshold corresponding to the current operation state, and then judge whether the oil pressure is abnormal through the comparison result, so as to monitor the oil pressure under different engine operation states, avoid potential safety hazards caused by abnormal oil pressure, and improve the stability of the engine operation.

[0239] It should be noted that since the oil plays an important role in lubrication and cooling during the entire operation of the engine, and when the oil pressure is insufficient, it will directly cause irreversible damage to the engine, such as scratches on relative moving parts and sharp local temperature rise. When there is a fault in the oil pressure, the driver must be notified to stop the machine immediately to avoid greater damage. When monitoring the oil pressure, it is necessary to select appropriate signals for the monitoring of the oil pressure. The monitoring of the oil pressure mainly uses the oil temperature and the oil pressure; the selection of these two variables will be introduced separately below.

[0240] Engine oil temperature: The lubrication of moving parts by engine oil mainly depends on the sufficient and continuous adhesion of the engine oil to the surfaces of the moving parts. The engine oil temperature mainly affects the viscosity of the engine oil. When the viscosity of the engine oil is too low, in order to maintain sufficient engine oil between the moving parts for lubrication, it is necessary to increase the supply of engine oil, that is, the engine oil pressure. Therefore, when detecting the engine oil pressure, the influence of the engine oil temperature on the boundary value is relatively large. There are two sources of the engine oil temperature: the engine oil temperature measured by the sensor and the engine oil temperature calculated by the module. Since the engine oil temperatures between the various moving parts of the engine are different, and the engine oil temperature measured by the sensor is only the engine oil temperature at a specific location, that is, the engine oil temperature at the outlet of the oil pump, and it cannot represent the overall engine oil temperature, so generally the engine oil temperature calculated by the module is selected as the engine oil temperature for engine oil pressure diagnosis.

[0241] In engine oil pressure diagnosis, different operating conditions and states require different pressure signals. For example, during engine starting and running conditions, the relative engine oil pressure needs to be used as the detection standard. This is because the engine oil pressure calculated from the engine oil boundary value at this time is calculated by subtracting the atmospheric pressure; in the case of engine oil pressure sensor sticking, the fault of the sensor itself is monitored, so the absolute pressure value must be used as the pressure signal for monitoring; in the calculation of the engine oil pressure sensor offset, it is to compare the deviation between the value read by the engine oil pressure sensor and the value read by the reference sensor, so the absolute pressure value is used.

[0242] Selection of engine oil pressure during engine operation: This engine oil pressure is a relative engine oil pressure value, which is used for the diagnosis of engine oil pressure when the engine starts to rotate and the parts move relative to each other. Since during engine operation, there may be a sudden drop in engine oil pressure due to the opening of the VVT, resulting in misdiagnosis.

[0243] Selection of engine oil pressure for sensor sticking: This variable is used for sensor sticking diagnosis, so this pressure value is the absolute pressure, and the filtered pressure value cannot be used. Because judging sticking is to judge whether the sensor value has fluctuations. When the sensor signal cannot reach fluctuations with the accuracy as the amplitude within a certain period of time, it proves that the sensor is stuck. In order to meet the above conditions, the selected absolute pressure value is used.

[0244] Selection of engine oil pressure for sensor offset: This variable is used to judge the offset of the engine oil pressure sensor, and the reference sensor is used as the judgment basis. Therefore, an absolute pressure sensor must be used. The selection of this pressure value is generally the same as that for sticking diagnosis pressure.

[0245] Optionally, judging whether the current actual engine oil pressure is abnormal according to the comparison result between the current actual engine oil pressure and the preset threshold includes:

[0246] When the engine is in the starting state, if the current actual oil pressure is less than the preset minimum boundary value, it is determined that the current actual oil pressure is abnormal;

[0247] When the engine is in the running state, if the current actual oil pressure is less than the preset minimum boundary value, it is determined that the current actual oil pressure is abnormal;

[0248] When the engine is in the starting state or the shutdown state, if the offset between the engine's oil pressure sensor and the reference sensor exceeds the preset offset threshold range, it is determined that the current oil pressure is abnormal.

[0249] Specifically, in the engine starting state, since only the self-torque value is considered and no external torque output is considered under the starting condition, the minimum pressure limit value can be obtained through the minimum pressure matching relationship based on the current speed and the current oil temperature. When the engine is in the starting state, if the current actual oil pressure is less than the preset minimum boundary value according to the current speed and the current oil temperature, it is determined that the current oil pressure of the engine may be abnormal and needs to be detected and repaired to eliminate potential hazards.

[0250] Table 24 is the minimum pressure matching relationship table:

[0251] Table 24

[0252] Temperature / Rotational Speed 0 r / min 500 r / min 800 r / min 1000 r / min 2500 r / min -40℃ 0 0 15 30 50 -20℃ 0 0 15 30 50 0℃ 0 0 30 50 50 20℃ 0 0 40 50 50 80℃ 0 0 30 50 50 120℃ 0 0 20 50 50

[0253] Furthermore, during the monitoring of the oil pressure during the engine operation, first, based on the current speed and the current oil temperature of the engine, a match is made through the preset minimum boundary value matching relationship to obtain the minimum boundary value of the oil pressure in the current operating state of the engine. When the current actual oil pressure is less than this minimum boundary value, it is determined that the current oil pressure is abnormal. This abnormality may be caused by various reasons and needs to be investigated to avoid damage to the engine caused by abnormal oil pressure. Among them, the minimum boundary value matching relationship includes the corresponding relationship between different combinations of the engine's speed and oil temperature and the minimum standard boundary value.

[0254] Moreover, the actual oil pressure at this time can be monitored through a hysteresis loop. When it is determined through the hysteresis loop monitoring that the oil pressure is within a reasonable range, that is, higher than or equal to the lower threshold value set by the hysteresis loop (such as 150 kPa), the system will set the corresponding flag to "pass", indicating that the current oil pressure is qualified and can meet the normal operation requirements of the equipment, and there is no need to trigger an alarm or further intervention measures. On the contrary, if the oil pressure drops below the lower threshold value set by the hysteresis loop (such as below 150 kPa), then the system will set the flag to "fail", which indicates that the oil pressure is too low and may affect the normal operation of the equipment (such as the engine). At this time, an alarm often needs to be issued in a timely manner to remind the operator to take corresponding measures, such as checking whether the oil quantity is insufficient, whether the oil pump is malfunctioning, and whether there is a leak in the oil pipeline, etc., to quickly restore the oil pressure to the normal range.

[0255] Table 23 is the minimum boundary value matching relationship table:

[0256] Table 23

[0257] Torque / Rotational Speed 500 r / min 8700 r / min 1000 r / min 2000 r / min 7000 r / min 0 N·m 0 50 50 50 50 100 N·m 0 50 50 50 50 200 N·m 0 50 50 50 50 300 N·m 0 50 50 50 50 400 N·m 0 50 50 50 50 500 N·m 0 50 50 50 50

[0258] Furthermore, since the oil pressure inside the engine is relatively stable when the engine is in the starting state or the stopping state, therefore, when the engine is in the starting state or the stopping state, the offset of the oil pressure sensor is monitored, so as to avoid the influence of oil pressure fluctuations on the offset of the oil pressure sensor and improve the accuracy of monitoring. The monitoring of the oil pressure offset is determined by the deviation between the boost pressure sensor and the ambient pressure sensor as the reference pressure and the oil pressure sensor. In order to ensure whether the offset of the monitoring sensor is within a reasonable range, that is, the positive offset and the negative offset, the corresponding positive offset and negative offset can be obtained respectively through the current oil temperature and the corresponding positive offset threshold table and negative offset threshold table. The monitoring of the oil pressure offset is determined by two conditions, namely: 1. Whether to monitor the offset; 2. Whether the offset is within the range of 0.9 times the allowable offset. This monitoring compares the pressure values of the two reference sensors with the oil pressure sensor, so as to avoid inaccurate diagnosis due to false alarms of one of the sensors as much as possible.

[0259] Table 21 is the positive offset threshold table:

[0260] Table 21

[0261] Engine Oil Temperature -40℃ 0℃ 20℃ 150℃ Positive Deviation Threshold 50 45 45 45

[0262] Table 22 is the negative offset threshold table:

[0263] Table 22

[0264] Engine Oil Temperature -40℃ 0℃ 20℃ 150℃ Negative Deviation Threshold -50 -45 -45 -45

[0265] The monitoring of the offset uses the average of the deviations of the oil pressure sensor from two reference sensors respectively to make a judgment. Here, the monitoring of the positive offset is introduced first. When the values of the oil pressure sensor, the boost pressure sensor, and the ambient pressure sensor are all greater than 0.9 times the reference maximum offset, it proves that the oil pressure sensor may have an over-offset at this time. At this time, the deviations of the pressure values of the oil pressure sensor from the two reference sensors are averaged to obtain an average value. The average value is compared with the limit offset when the offset monitoring is enabled. If it is greater than the positive offset threshold, the positive offset of the oil pressure sensor is over the limit. The monitoring method of the negative offset is the same as that of the positive offset. However, since the negative offset is a negative value, the judgment criterion is less than the negative offset threshold of the negative offset. Therefore, when it is judged that the offset of the sensor is greater than the positive offset threshold or less than the negative offset threshold, it is judged that the offset of the sensor exceeds the offset threshold range, and then it is judged that the oil pressure sensor has an offset. It is necessary to judge the cause of the offset according to the specific situation. For example, reasons such as oil pressure sensor failure, oil circuit blockage or leakage, or oil pump failure may all cause the offset of the oil pressure sensor.

[0266] It should be noted that when monitoring the oil pressure, it is necessary to judge the status included in the monitoring diagnosis. This status can be divided into: judgment of states such as starting, running, and offset. Among them, the judgment of jamming can be continuously carried out after the Electronic Control Unit (ECU) is awakened. Therefore, the judgment of entering the state is divided into: judgment under the general running state of the engine; judgment under the starting state of the engine; judgment under the pre-running and post-running states of the engine. Before judging the state of the engine at this time and the diagnosis that should be carried out, it is first necessary to judge whether it is possible to enter the fault diagnosis, that is, when a hardware problem of the sensor is detected, etc., it is not necessary to enter this diagnostic module anymore;

[0267] The entry conditions for entering the fault diagnosis are:

[0268] 1) The oil temperature is greater than a fixed value and no longer less than the threshold; this is because when the oil temperature is too low, problems will occur with the oil pump. For example, the fixed value is 80 °C and the threshold is 70 °C. After the oil temperature rises above 80 °C and then drops, it remains greater than 70 °C;

[0269] 2) The ECU is powered on;

[0270] 3) There is no input of an oil pressure fault code.

[0271] The judgment basis for entering the normal operation diagnosis of the engine is:

[0272] 1. The on-board diagnostics (OBD) monitoring is activated, and the diagnosis is based on the OBD activation.

[0273] 2. The conditions for entering the diagnosis are met to rule out engine faults caused by other reasons.

[0274] 3. When the engine speed is greater than the operating threshold, it indicates that the engine has completed starting. However, to avoid the impact of starting on subsequent processes, a delay process is required for a period of time.

[0275] When the normal operation diagnosis conditions are met, the monitoring of the normal operation stage of the engine can be carried out.

[0276] Determine whether the engine is in the starting state:

[0277] The judgment conditions are as follows: being in the starting state means that the engine speed is not greater than the starting threshold, and adding a state delay together serves as a sign that the engine has not completed starting; using the engine speed greater than the starting threshold as the judgment that the engine is not in the starting state. Taking the engine speed less than 10 r / min as the starting flag bit. Of course, the oil pressure diagnosis in the starting state is also carried out on the basis that the conditions for entering the diagnosis are met.

[0278] Determine the conditions for entering the offset diagnosis:

[0279] The offset diagnosis of the oil pressure sensor is based on the deviation between the sensor and the reference sensor. The reference sensors selected are the ambient pressure sensor and the boost pressure sensor. To make the reference sensor and the oil pressure sensor comparable, the following two points must be met:

[0280] 1. The engine is not running;

[0281] 2. There is no residual oil pressure in the oil rail.

[0282] To determine that the engine is not running and there is no residual oil pressure in the oil rail, the engine speed is used for judgment. That is, when the speed is less than 0.1 r / min, the engine is considered to be stopped; when the running time at a speed below 100 r / min is greater than the speed threshold (where the speed threshold can be determined by the oil temperature), it is considered that there is no residual oil pressure in the oil rail. When the above two conditions are both met, the basic conditions for offset detection are satisfied.

[0283] It should also be noted that when monitoring the oil pressure during the engine operation, first, the entry conditions for oil pressure diagnosis need to be met; second, the conditions for entering the offset monitoring need to be satisfied; of course, there should also be no sensor electrical faults issued by the Flame Ionization Detector (FID); finally, the pre-operation condition is judged.

[0284] Judgment of the pre-operation condition: First, the starting point needs to be judged, that is, when the ECU is powered on, it is the starting point of pre-operation; second, the end point needs to be judged, which can be divided into two categories: the start of the starting motor; the recovery after a significant voltage drop of the battery voltage. When both conditions are met, it is judged that it is in the pre-operation stage (here, the engine speed can also be used for judgment, but the speed sensor is not very accurate at the moment of starting, so the battery voltage is used as the judgment basis). When all the above conditions are met, the pre-operation execution condition is satisfied.

[0285] Diagnosis of the oil pressure sensor during the post-operation of the engine:

[0286] First, the entry conditions for oil pressure diagnosis need to be met; second, the conditions for entering the offset monitoring need to be satisfied; of course, there should also be no sensor electrical faults; finally, the post-operation condition is judged.

[0287] Judgment of the post-operation condition: When the starting motor is not running and it is judged that the engine ignition switch is off, it proves that the engine has stopped. This condition is when the key has been powered off and the starting motor has not started again. When the state of the offset has been judged, there is no need to enter the monitoring of the oil pressure sensor during post-operation.

[0288] As Figure 3 shown, an oil pressure control device 300 provided by an embodiment of the present invention includes:

[0289] A processing module 310, configured to determine a target temperature range corresponding to the current engine oil temperature obtained in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit oil temperature and a lower limit oil temperature;

[0290] An interpolation calculation module 320, configured to perform interpolation calculation based on a first oil pressure corresponding to the upper limit oil temperature of the current engine parameters and a second oil pressure corresponding to the lower limit oil temperature of the current engine parameters to determine an expected oil pressure corresponding to the current engine parameters at the current oil temperature, where the current engine parameters include the current engine speed and the current desired torque;

[0291] A control module 330, configured to determine an oil pump control duty ratio through a control algorithm according to the expected oil pressure, and control the oil pump according to the oil pump control duty ratio.

[0292] The oil pressure control device of this embodiment is used to implement the oil pressure control method as described above. Its advantages compared with the prior art are the same as those of the above-mentioned oil pressure control method compared with the prior art, and will not be elaborated here.

[0293] As Figure 4 shown, a vehicle 400 provided by an embodiment of the present invention includes a memory 410 and a processor 420; the memory 410 is used to store a computer program; the processor 420 is used to implement the oil pressure control method as described above when executing the computer program.

[0294] Or, a vehicle 400 includes a memory 410 and a processor 420 coupled to the memory 410; the memory 410 is configured to store a computer program; the processor 420 is configured to perform the following operations when executing the computer program:

[0295] Determine a target temperature range corresponding to the current engine oil temperature obtained in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit oil temperature and a lower limit oil temperature;

[0296] Perform interpolation calculation based on a first oil pressure corresponding to the engine current parameters at the upper limit oil temperature and a second oil pressure corresponding to the engine current parameters at the lower limit oil temperature to determine an expected oil pressure corresponding to the engine current parameters at the current oil temperature, where the engine current parameters include the current engine speed and the current desired torque;

[0297] Determine an oil pump control duty ratio according to the expected oil pressure through a control algorithm, and control the oil pump according to the oil pump control duty ratio.

[0298] A computer-readable storage medium provided by an embodiment of the present invention has a computer program stored thereon. When the computer program is executed by a processor, the oil pressure control method as described above is implemented.

[0299] Or, a non-volatile computer-readable storage medium has a computer program stored thereon. When the computer program is executed by a processor, the processor is caused to perform the following operations:

[0300] Determine a target temperature range corresponding to the current engine oil temperature obtained in a plurality of consecutive temperature ranges, where the target temperature range includes an upper limit oil temperature and a lower limit oil temperature;

[0301] Interpolate based on the first oil pressure corresponding to the current engine parameters at the upper limit oil temperature and the second oil pressure corresponding to the current engine parameters at the lower limit oil temperature to determine the expected oil pressure corresponding to the current engine parameters at the current oil temperature, where the current engine parameters include the current engine speed and the current desired torque;

[0302] Determine the oil pump control duty ratio through a control algorithm based on the expected oil pressure, and control the oil pump according to the oil pump control duty ratio.

[0303] Vehicle 400, which can be a server or a client of the present invention, will now be described. It is an example of a hardware device to which various aspects of the present invention can be applied. Vehicle 400 is intended to represent various forms of digital electronic computer devices, such as, laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. Vehicle 400 can also represent various forms of mobile devices, such as, personal digital processors, cellular phones, smart phones, wearable devices, and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or claimed herein.

[0304] Vehicle 400 includes a computing unit that can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) or a computer program loaded from a storage unit into a random access memory (RAM). In the RAM, various programs and data required for device operation can also be stored. The computing unit, ROM, and RAM are connected to each other through a bus. An input / output (I / O) interface is also connected to the bus.

[0305] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments of the present invention. In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0306] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A method for controlling oil pressure, characterized in that: include: Determining a target temperature interval corresponding to the acquired current oil temperature of the engine in a plurality of continuous temperature intervals, wherein the target temperature interval includes an upper limit oil temperature and a lower limit oil temperature; Determine the expected oil pressure corresponding to the current parameters of the engine at the current oil temperature by performing interpolation calculation according to a first oil pressure corresponding to the current parameters of the engine at the upper oil temperature limit and a second oil pressure corresponding to the current parameters of the engine at the lower oil temperature limit, wherein the current parameters of the engine include a current speed and a current expected torque of the engine; An oil pump control duty ratio is determined by a control algorithm according to the desired oil pressure, and the oil pump is controlled according to the oil pump control duty ratio.

2. The oil pressure control method according to claim 1, characterized in that: Before interpolating the first oil pressure corresponding to the current engine parameter at the upper oil temperature and the second oil pressure corresponding to the current engine parameter at the lower oil temperature, the oil pressure control method further includes: respectively determining a first oil pressure matching relationship corresponding to the upper oil temperature limit and a second oil pressure matching relationship corresponding to the lower oil temperature limit; The first oil pressure is determined in the first oil pressure matching relationship according to the current parameters of the engine, and the second oil pressure is determined in the second oil pressure matching relationship according to the current parameters of the engine, wherein the first oil pressure matching relationship and the second oil pressure matching relationship respectively include the corresponding relationship between the current parameters of the engine and the oil pressure at the corresponding temperature.

3. The oil pressure control method according to claim 1, characterized in that: The interpolation calculation is performed based on a first oil pressure corresponding to the current engine parameter at the upper oil temperature limit and a second oil pressure corresponding to the current engine parameter at the lower oil temperature limit to determine an expected oil pressure corresponding to the current engine parameter at the current oil temperature limit, including: Determine the ratio between the difference between the current engine oil temperature and the lower limit engine oil temperature and the temperature width of the temperature interval to obtain a first pressure proportional factor; determine the ratio between the difference between the upper limit engine oil temperature and the current engine oil temperature and the temperature width to obtain a second pressure proportional factor; wherein the temperature width is the difference between the upper limit engine oil temperature and the lower limit engine oil temperature; The desired oil pressure is obtained by adding a product of the first oil pressure and the first pressure proportional factor and a product of the second oil pressure and the second pressure proportional factor.

4. The oil pressure control method according to claim 1, characterized in that: The step of determining the oil pump control duty cycle by a control algorithm according to the expected oil pressure includes: Determine a target oil pressure interval corresponding to the expected oil pressure in a plurality of continuous oil pressure intervals, and perform interpolation calculation based on a first duty ratio corresponding to the current speed at the upper limit oil pressure of the target oil pressure interval and a second duty ratio corresponding to the current speed at the lower limit oil pressure of the target oil pressure interval to determine a feedforward control duty ratio corresponding to the current speed at the expected oil pressure; Determining a closed-loop control duty cycle according to the acquired current actual oil pressure and the desired oil pressure; The feedforward control duty cycle and the closed-loop control duty cycle are added to obtain the oil pump control duty cycle.

5. The oil pressure control method according to claim 4, characterized in that: Before performing interpolation calculation based on the first duty ratio corresponding to the current speed at the upper limit oil pressure of the target oil pressure range and the second duty ratio corresponding to the current speed at the lower limit oil pressure of the target oil pressure range, the oil pressure control method further includes: respectively determining a first duty ratio matching relationship corresponding to the upper limit oil pressure and a second duty ratio matching relationship corresponding to the lower limit oil pressure; The first duty cycle is determined in the first duty cycle matching relationship according to the current oil temperature and the current speed, and the second duty cycle is determined in the second duty cycle matching relationship according to the current oil temperature and the current speed, wherein the first duty cycle matching relationship and the second duty cycle matching relationship respectively include the corresponding relationship between the current oil temperature and the current speed and the duty cycle under the corresponding oil pressure.

6. The oil pressure control method according to claim 4, characterized in that: The interpolation calculation is performed based on a first duty ratio corresponding to the current speed at the upper limit oil pressure of the target oil pressure interval and a second duty ratio corresponding to the current speed at the lower limit oil pressure of the target oil pressure interval to determine a feedforward control duty ratio corresponding to the current speed at the expected oil pressure, including: Determine the ratio between the difference between the expected oil pressure and the lower oil pressure and the pressure width of the target oil pressure interval to obtain a first duty ratio factor; determine the ratio between the difference between the upper oil pressure and the current oil pressure and the pressure width to obtain a second duty ratio factor, wherein the pressure width is the difference between the upper oil pressure and the lower oil pressure; The feedforward control duty cycle is obtained by adding a product of the first duty cycle and the first duty cycle proportional factor and a product of the second duty cycle oil pressure and the second duty cycle proportional factor.

7. The oil pressure control method according to claim 4, characterized in that: Determining the closed-loop control duty cycle according to the acquired current actual oil pressure and the expected oil pressure includes: The difference between the expected oil pressure and the expected oil pressure obtained in the previous sampling period is determined as the expected oil pressure deviation, and the ratio of the expected oil pressure deviation to the sampling period is multiplied by a preset compensation coefficient after filtering to obtain a duty cycle compensation amount; Determine the difference between the current actual oil pressure and the actual oil pressure obtained in the previous sampling period as the actual oil pressure deviation, and multiply the ratio of the actual oil pressure deviation to the sampling period by a preset differential coefficient after filtering to obtain a differential duty cycle; Determine the difference between the current actual oil pressure and the expected oil pressure as a current oil pressure deviation, and determine the product of the current oil pressure deviation and a preset proportionality coefficient as a proportional duty cycle; The difference between the actual oil pressure and the expected oil pressure corresponding to each sampling period is summed and then multiplied by a preset integral coefficient to obtain an initial integral duty cycle, and the product of a preset duty cycle excess limit value and a correction coefficient is subtracted from the initial integral duty cycle to obtain an integral duty cycle; The duty cycle compensation amount, the differential duty cycle, the proportional duty cycle and the integral duty cycle are added together to obtain the closed-loop control duty cycle.

8. The oil pressure control method according to claim 1, characterized in that: Also includes: monitoring the actual current oil pressure of the engine; When the current actual oil pressure exceeds a preset stuck oil pressure range, determining that the oil pressure sensor is stuck; and / or, Based on the current state of the engine, it is determined whether the current actual oil pressure is abnormal by comparing the current actual oil pressure with a preset threshold.

9. The oil pressure control method according to claim 1, characterized in that: The step of determining whether the current actual engine oil pressure is abnormal by comparing the current actual engine oil pressure with a preset threshold value includes: When the engine is in a starting state, if the current actual engine oil pressure is less than a preset minimum boundary value, determining that the current actual engine oil pressure is abnormal; When the engine is in a running state, if the current actual engine oil pressure is less than a preset minimum boundary value, determining that the current actual engine oil pressure is abnormal; When the engine is in a start state or a stop state, if the offset between the oil pressure sensor of the engine and the reference sensor exceeds a preset offset threshold range, it is determined that the current oil pressure is abnormal.

10. An oil pressure control device, characterized in that: include: A processing module, used to determine a target temperature interval corresponding to the acquired current oil temperature of the engine in a plurality of continuous temperature intervals, wherein the target temperature interval includes an upper limit oil temperature and a lower limit oil temperature; an interpolation calculation module, configured to perform interpolation calculation according to a first oil pressure corresponding to a current engine parameter at the upper oil temperature limit and a second oil pressure corresponding to the current engine parameter at the lower oil temperature limit, to determine an expected oil pressure corresponding to the current engine parameter at the current oil temperature limit, wherein the current engine parameter includes a current engine speed and a current expected torque; A control module is used to determine an oil pump control duty cycle through a control algorithm according to the expected oil pressure, and control the oil pump according to the oil pump control duty cycle.

11. A vehicle, characterized in that: including memory and processor; The memory is used to store computer programs; The processor is used to implement the oil pressure control method according to any one of claims 1 to 9 when executing the computer program.

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