Electromagnetic valve closed loop control system for engine variable displacement oil pump

Abstract

This invention discloses a closed-loop control system for a solenoid valve of a variable displacement oil pump in an engine, relating to the field of pressure control technology. The system includes: matching a target oil pressure based on engine operating condition information; determining the equivalent viscosity of the oil through the real-time dynamic evolution characteristics of oil temperature and pressure in the hydraulic medium state, and generating oil pressure regulation control reference information; a duty cycle adjustment module, which dynamically adjusts the response sensitivity of the pressure regulation loop based on the oil pressure regulation control reference information and the equivalent viscosity of the oil to adapt to the changes in motion damping of the hydraulic medium under different temperature conditions, obtaining a target control duty cycle signal for the solenoid valve; and a chatter overlay module, which matches a corresponding chatter frequency and amplitude according to the equivalent viscosity of the oil, and loads the chatter frequency and amplitude onto the target control duty cycle signal of the solenoid valve to generate a solenoid valve drive control command; thereby improving engine lubrication consistency and fuel economy.

Description

Technical Field

[0001] This invention relates to the field of pressure control technology, and in particular to a closed-loop control system for a solenoid valve of a variable displacement engine oil pump. Background Technology

[0002] With the increasing demands for engine energy conservation and emission reduction, as well as improved vehicle energy efficiency, variable displacement oil pumps, capable of dynamically adjusting oil supply according to engine operating conditions, offer significant advantages in reducing pumping losses and improving fuel economy. They have gradually replaced traditional fixed displacement oil pumps and are widely used in passenger and commercial vehicle powertrain systems. Existing variable displacement oil pumps typically use solenoid valves to control the pressure in the pump's internal control chamber, thereby changing the swashplate angle or the position of the eccentric mechanism to achieve continuous adjustment of the oil pump's displacement. To ensure that the engine receives appropriate oil pressure under different speeds, loads, and lubrication requirements, relevant control systems generally incorporate main oil passage pressure feedback signals and employ closed-loop control to adjust the solenoid valve drive signal in real time. This allows the oil pressure to stably track the target pressure value, forming an important component of the engine lubrication system.

[0003] In existing closed-loop control systems, solenoid valve control strategies are typically based on fixed or segmented calibrated control gain parameters and are primarily adjusted according to pressure deviation. However, during actual engine operation, the physical properties of engine oil, as a hydraulic medium, fluctuate significantly with temperature changes. In particular, changes in the kinematic viscosity of the engine oil directly affect the flow damping characteristics of the hydraulic system, thereby altering the main oil passage pressure build-up speed and dynamic response characteristics. When the engine oil temperature changes significantly, fixed control parameters often fail to reflect changes in the hydraulic medium's damping state in a timely manner, easily leading to pressure response lag or mismatched adjustment sensitivity, resulting in inconsistent closed-loop control performance under different operating conditions. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a closed-loop control system for the solenoid valve of a variable displacement oil pump for an engine to solve the problem of difficulty in matching the response sensitivity of the solenoid valve closed-loop control due to changes in the viscosity and damping characteristics of the hydraulic medium caused by changes in oil temperature.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] This invention provides a closed-loop control system for a solenoid valve of a variable displacement oil pump for an engine, comprising:

[0008] The data acquisition module obtains the engine operating status and hydraulic medium status, and outputs engine operating condition information.

[0009] The identification module matches the target oil pressure based on engine operating condition information; and determines the equivalent viscosity of the oil by the dynamic evolution characteristics of real-time oil temperature and pressure in the hydraulic medium state, and generates oil pressure regulation and control reference information.

[0010] The duty cycle adjustment module, based on the oil pressure regulation control reference information, dynamically adjusts the response sensitivity of the pressure regulation circuit with the equivalent viscosity of the engine oil to adapt to the motion damping changes of the hydraulic medium under different temperature conditions, and obtains the target control duty cycle signal of the solenoid valve.

[0011] The flutter superposition module matches the corresponding flutter frequency and flutter amplitude according to the equivalent viscosity of the engine oil, and loads the flutter frequency and flutter amplitude onto the target control duty cycle signal of the solenoid valve to generate the solenoid valve drive control command.

[0012] The drive feedback module drives the solenoid valve to operate according to the solenoid valve drive control command, adjusts the amount of oil entering the control chamber of the variable displacement oil pump, and collects the oil pressure in the main oil passage as a feedback signal to update the engine operating condition information.

[0013] Preferably, the method for outputting engine operating condition information includes:

[0014] The system acquires the crankshaft speed and throttle opening during engine operation, as well as the feedback pressure value and real-time oil temperature signal in the hydraulic medium, performs voltage regulation and low-pass filtering, and outputs a smooth DC level signal.

[0015] The smoothed DC level signal is converted into a digital discrete signal, and the digital discrete signal is restored to a physical quantity representation signal. After signal fusion, the engine operating condition information is output.

[0016] Preferably, the matching of the target oil pressure based on engine operating condition information includes:

[0017] The crankshaft speed and throttle opening in the engine operating information are used as horizontal and vertical axis indices respectively to locate the preset target pressure logic matrix, and the basic target pressure value is output.

[0018] The target pressure compensation gain is determined based on the crankshaft speed, and the temperature difference characteristics between the real-time oil temperature signal and the reference temperature are obtained. The temperature difference characteristics are then quantized and mapped based on the target pressure compensation gain to obtain the pressure correction amount. The pressure correction amount is then coupled with the base target pressure value to determine the target oil pressure.

[0019] Preferably, the method for generating oil pressure regulation and control reference information includes:

[0020] Extract feedback pressure values ​​according to the sampling period and obtain the dynamic evolution characteristics of pressure at the current sampling time relative to the previous sampling time;

[0021] The kinematic viscosity reference value is determined based on the real-time oil temperature signal, and the kinematic viscosity reference value is compensated and corrected by the deviation of the pressure dynamic evolution characteristics from the standard pressure rise rate, so as to obtain the equivalent viscosity of the oil.

[0022] The equivalent viscosity of the engine oil is logically correlated with the target engine oil pressure and the data is encapsulated to output oil pressure regulation and control reference information.

[0023] Preferably, the method for obtaining the target control duty cycle signal of the solenoid valve includes:

[0024] Determine the pressure follow-up deviation between the target oil pressure and the feedback pressure value in the oil pressure regulation control reference information;

[0025] The initial regulation parameters of the pressure regulation loop are obtained as the basic control gain; the basic correction gain is determined based on the equivalent viscosity of the engine oil to determine the motion damping state of the hydraulic medium.

[0026] Based on the change trend of the equivalent viscosity of the engine oil relative to the motion damping determined in the previous sampling period, the basic control gain and the basic correction gain are fused and adjusted to form the response sensitivity after viscosity correction.

[0027] The pressure follow-up deviation is calculated by using the response sensitivity after viscosity correction to generate a pressure regulation control quantity. The pressure regulation control quantity is then combined with the duty cycle reference value to obtain the target control duty cycle signal of the solenoid valve.

[0028] Preferably, the step of matching the corresponding chatter frequency and chatter amplitude based on the equivalent viscosity of the engine oil includes:

[0029] The equivalent viscosity of engine oil is mapped to the viscosity grade of engine oil under the damping state of hydraulic medium motion;

[0030] Based on the oil viscosity grade, the flow damping characteristic range corresponding to the hydraulic medium is determined, and the corresponding chatter compensation matching rule is selected; adaptive adjustment is performed on the chatter frequency and chatter amplitude in the solenoid valve drive signal so that the chatter frequency and chatter amplitude change in tandem with the change of the flow damping characteristics of the hydraulic medium;

[0031] The combined adjustment of the flutter frequency and flutter amplitude is quantized to generate the target flutter frequency and target flutter amplitude for the current control cycle.

[0032] Preferably, the method for generating solenoid valve drive control commands includes:

[0033] A waveform sequence signal with a corresponding period is generated based on the target flutter frequency, and the amplitude of the waveform sequence signal is adjusted using the target flutter amplitude to obtain a duty cycle compensation signal.

[0034] The duty cycle compensation signal and the target control duty cycle signal of the solenoid valve are logically synthesized to generate a pulse width modulation form of solenoid valve drive control command.

[0035] Preferably, the step of using feedback signals to update engine operating condition information includes:

[0036] The solenoid valve drive control command is converted into a power command and the drive current is output to the solenoid valve coil to drive the solenoid valve to act and regulate the amount of oil entering the control chamber of the variable displacement oil pump.

[0037] Collect the physical variables corresponding to the oil pressure in the main oil passage and convert them into feedback signals in the form of electrical signals;

[0038] The feedback signal is converted into a digital form of feedback pressure value, and the feedback pressure value is used to perform real-time updates on engine operating condition information.

[0039] Preferably, the method of compensating for and correcting the kinematic viscosity reference value by utilizing the deviation between the dynamic evolution characteristics of pressure and the standard pressure rise rate includes:

[0040] The dynamic evolution characteristics of pressure are compared with the standard pressure rise rate to determine the damping deviation ratio, which reflects the degree of deviation in the pressure build-up process.

[0041] Incremental compensation is performed on the kinematic viscosity benchmark value based on the damping deviation ratio to determine the equivalent viscosity of the engine oil.

[0042] Preferably, the determination of the trend of motion damping variation includes:

[0043] Based on the evolution trend of the equivalent viscosity of the oil in the current control cycle and the previous control cycle, determine the change range of the hydraulic medium motion damping state.

[0044] The change range is correlated with the equivalent viscosity of the engine oil in the current control cycle to obtain a dimensionless damping change ratio, which is then used as the trend of motion damping change within the current control cycle.

[0045] The beneficial effects of this invention are as follows: By real-time acquisition of multi-dimensional engine operating parameters, the equivalent viscosity of the engine oil is identified online using the main oil passage pressure change characteristics and oil temperature, and the PID control gain and the frequency and amplitude of the solenoid valve chatter signal are dynamically corrected accordingly, achieving deep coupling between the control logic and the physical properties of the hydraulic medium; it is used for the precise adjustment process of variable displacement oil pumps, eliminating the hysteresis effect and response delay of the solenoid valve under different viscosity media, and automatically compensating for changes in system motion damping; throughout the entire temperature range and the entire oil life cycle, it ensures that the main oil passage pressure tracking is fast, accurate, stable, and reliable, improving engine lubrication consistency and fuel economy. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a schematic diagram of the solenoid valve closed-loop control system of the variable displacement oil pump in the engine of the present invention.

[0048] Figure 2 This is a flowchart illustrating the output of oil pressure regulation and control reference information in this invention.

[0049] Figure 3 This is a flowchart of obtaining the target control duty cycle signal of the solenoid valve in this invention.

[0050] Figure 4 This is a flowchart for generating the target flutter frequency and target flutter amplitude within the current control cycle in this invention. Detailed Implementation

[0051] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0052] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0053] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0054] Reference Figure 1 , Figure 2 , Figure 3 and Figure 4 As one embodiment of the present invention, this embodiment provides a closed-loop control system for a solenoid valve of a variable displacement oil pump in an engine, comprising the following steps:

[0055] Methods for outputting engine operating condition information include:

[0056] The system acquires crankshaft speed and throttle opening during engine operation, as well as feedback pressure and real-time oil temperature signals in the hydraulic medium. It then performs voltage regulation and low-pass filtering to output a smooth DC level signal.

[0057] It should be noted that the crankshaft speed and throttle opening during engine operation, as well as the feedback pressure value and real-time oil temperature signal in the hydraulic medium, are acquired through the hardware interface and transmitted to the level adjustment circuit. The level adjustment circuit performs voltage division and amplitude limiting on all signals, adjusting the voltage amplitude of all signals to the preset analog-to-digital converter range, for example, 0V to 5V. Subsequently, all signals after amplitude limiting are connected to the low-pass filter circuit. The low-pass filter circuit filters out high-frequency noise interference caused by sensor jitter or electromagnetic induction in all signals by setting the cutoff frequency, and finally outputs a smooth DC level signal.

[0058] The smoothed DC level signal is converted into a digital discrete signal, and the digital discrete signal is restored to a physical quantity representation signal. After signal fusion, the engine operating condition information is output.

[0059] Specifically, the smoothed DC level signal output from the low-pass filter circuit is transmitted to the input of the analog-to-digital converter (ADC). The ADC performs voltage quantization and encoding on the smoothed DC level signal according to a preset sampling frequency of 1kHz, converting it into a corresponding digital discrete signal. Using a signal scaling instruction combined with an offset zero-point calibration path (suggested scaling factor value of 0.01 and offset value of 0), the digital discrete signal is restored to physical quantity representation signals corresponding to crankshaft speed, throttle opening, feedback pressure value, and real-time oil temperature. The restored physical signals are then spatially weighted and load-arranged to complete signal fusion and output engine operating condition information.

[0060] Based on engine operating condition information, the corresponding target oil pressure is matched, including:

[0061] The crankshaft speed and throttle opening from the engine operating information are used as horizontal and vertical axis indices to locate the preset target pressure logic matrix, and the basic target pressure value is output.

[0062] It should be noted that by parsing engine operating condition information to extract crankshaft speed and throttle opening, crankshaft speed is used as the horizontal axis search vector and throttle opening is used as the vertical axis search vector. In the high-dimensional lookup table space, bilinear correlation fitting logic is used to locate the corresponding coordinate point in the preset target pressure logic matrix, thereby extracting the basic target pressure value that matches the current operating condition.

[0063] It should be noted that the process of constructing the preset target pressure logic matrix is ​​as follows: traverse the full speed range and full load range of the engine, record the main oil passage pressure value when the engine reaches the optimal lubrication performance at each operating point, and store the crankshaft speed, throttle opening and the corresponding main oil passage pressure value in the form of key-value pairs to form a two-dimensional mapping relationship target pressure logic matrix.

[0064] The target pressure compensation gain is determined based on the crankshaft speed, and the temperature difference characteristics between the real-time oil temperature signal and the reference temperature are obtained. The temperature difference characteristics are then quantized and mapped based on the target pressure compensation gain to obtain the pressure correction amount. The pressure correction amount is then coupled with the base target pressure value to determine the target oil pressure.

[0065] It should be noted that the crankshaft speed is extracted by parsing the engine operating information. The crankshaft speed is used as the search key and the address matching is performed in the sensitivity feature mapping table. If the crankshaft speed is between two calibration points, the values ​​of the adjacent calibration points are used for linear weighted transformation to output the target pressure compensation gain corresponding to the current crankshaft speed.

[0066] It should be noted that the construction process of the sensitivity feature mapping table is as follows: During the engine calibration test, by controlling the oil circulation loop to be under different constant speed conditions and adjusting the oil temperature to generate gradient changes, the slope of the response change of the main oil passage pressure with temperature fluctuation at each speed node is recorded. The crankshaft speed and the corresponding response change slope are stored in the storage medium in a one-to-one correspondence to form a sensitivity feature mapping table describing the effect of speed on temperature-pressure sensitivity adjustment.

[0067] Acquire the temperature difference characteristics between the real-time oil temperature signal and the reference temperature (80℃ in the example); fuse the temperature difference characteristics with the target pressure compensation gain to obtain a preliminary compensation value reflecting the intensity of temperature compensation; map the preliminary compensation value to the pressure correction range (-0.5 bar to 0.5 bar in the example), and convert the preliminary compensation value into a pressure correction amount by limiting the range of variation of the preliminary compensation value and performing discretization numerical alignment; couple the pressure correction amount with the base target pressure value to determine the target oil pressure.

[0068] Methods for generating oil pressure regulation and control reference information include:

[0069] Traditional variable displacement oil pump control strategies typically rely solely on real-time oil temperature signals to look up values ​​in tables to compensate for viscosity changes. However, this ignores the complex physical evolution of the hydraulic medium during actual operation. Over long-term operation, oil deteriorates due to thermal oxidation, mechanical shear thinning, or differences in viscosity indices between different brands, causing a shift in the nominal temperature-viscosity relationship. Temperature sensors alone cannot detect the true flow resistance of the medium, leading to inconsistent responses in the pressure regulation system, such as pressure build-up lag or overshoot, when the oil ages or operating conditions change drastically. To eliminate the impact of these physical characteristic drifts on control accuracy, this solution captures the transient response characteristics of the hydraulic circuit to inversely pinpoint the true physical properties of the medium. The specific implementation process is as follows:

[0070] The feedback pressure value is extracted according to the sampling period, and the dynamic evolution characteristics of the pressure at the current sampling time relative to the previous sampling time are obtained.

[0071] Specifically, feedback pressure values ​​are continuously extracted from engine operating condition information according to the sampling period (10ms in the example), and the state evolution displacement of the feedback pressure value obtained at the current sampling time and the feedback pressure value obtained at the previous sampling time is obtained. Then, combined with the time step of the sampling period (0.01s in the example), the dynamic evolution slope of the feedback pressure on the time axis is extracted through slope mapping processing, which is used as the dynamic evolution feature of pressure.

[0072] The kinematic viscosity reference value is determined based on the real-time oil temperature signal, and the kinematic viscosity reference value is compensated and corrected by the deviation of the pressure dynamic evolution characteristics from the standard pressure rise rate, so as to obtain the equivalent viscosity of the oil.

[0073] Specifically, the real-time oil temperature signal is input as an independent variable into the kinematic viscosity analysis function, expressed as follows: ;in, This is the kinematic viscosity reference value. It is the first viscosity coefficient (example value is 0.05). It is the second viscosity coefficient (example value is 1200). It is the viscosity shift constant (example value is 273.15). It is a natural constant. It is a real-time oil temperature signal;

[0074] The dynamic evolution characteristics of pressure are compared with the standard pressure rise rate (example value is 5 bar / s), and the gain compensation is performed on the kinematic viscosity reference value according to the degree of deviation generated by the comparison. By correcting the fluctuation of the kinematic viscosity reference value caused by the difference in the physical properties of the medium, the equivalent viscosity of the engine oil is determined.

[0075] It should be noted that the first viscosity coefficient, the second viscosity coefficient, and the viscosity offset constant are determined based on the temperature-viscosity characteristic reference curve of a specific type of hydraulic medium. Specifically, the dynamic viscosity samples of the hydraulic medium are collected using a rotational viscometer at a preset temperature gradient, and the distribution law of the medium density with temperature change is combined to convert it into a kinematic viscosity dataset. Then, a nonlinear least squares method is introduced to perform a global optimal fit on the dataset. Through iterative approximation, the sum of squared residuals between the output value of the analytical function and the experimental observation value is minimized, thereby extracting the first viscosity coefficient, the second viscosity coefficient, and the viscosity offset constant that characterize the physical properties of the medium.

[0076] The equivalent viscosity of the engine oil is logically correlated with the target engine oil pressure and the data is encapsulated to output oil pressure regulation and control reference information.

[0077] Specifically, the identified equivalent oil viscosity and the determined target oil pressure are reassembled and spatially mapped according to a predetermined data frame structure. For example, the equivalent oil viscosity is mapped to a preset high-order segment, such as the high 16 bits of a 32-bit data packet, through a level shift operation, and the target oil pressure is aligned to the corresponding low-order segment, such as the low 16 bits of the data packet. Then, through protocol payload encapsulation, the equivalent oil viscosity and target oil pressure at different spatial weights are nested and combined into a complete data packet, outputting oil pressure regulation control reference information containing multi-dimensional control features.

[0078] By introducing dynamic pressure evolution characteristics (such as the slope of pressure evolution over time), a real-time profile of the physical properties of the hydraulic medium is achieved. By utilizing the deviation between the actual pressure rise rate and the standard rise rate, incremental compensation is applied to the kinematic viscosity benchmark, accurately locking in the current equivalent viscosity of the engine oil. This eliminates interference caused by drift in the physical properties of the medium, ensuring that subsequent control parameters are always based on the true hydraulic damping state, significantly improving the system's robustness to different oil conditions.

[0079] Methods for obtaining the target control duty cycle signal of the solenoid valve include:

[0080] Determine the pressure follow-up deviation between the target oil pressure and the feedback pressure value in the oil pressure regulation control reference information.

[0081] Specifically, the target oil pressure is extracted from the oil pressure regulation control reference information, and the feedback pressure in the current operating condition information is obtained at the same time. The target oil pressure and the feedback pressure are connected to the deviation identification channel. Through state alignment and deviation extraction, the instantaneous follow-up displacement between the two is obtained, which is used as the pressure follow-up deviation that characterizes the current pressure regulation error state of the main oil passage.

[0082] The initial adjustment parameters of the pressure regulation loop are obtained as the basic control gain; the basic correction gain is determined based on the equivalent viscosity of the engine oil to determine the motion damping state of the hydraulic medium.

[0083] Specifically, the initial adjustment parameters corresponding to the pressure regulation loop are read from the non-volatile memory. The initial adjustment parameters include the proportional gain parameter for proportional regulation and the integral gain parameter for integral regulation. The proportional gain parameter and the integral gain parameter together constitute the basic control gain, which is used to describe the response characteristics of the pressure regulation loop under standard hydraulic medium conditions.

[0084] By analyzing the equivalent viscosity of the oil encapsulated in the oil pressure regulation control reference information, the equivalent viscosity of the oil is used as a quantitative characterization of the damping state of the hydraulic medium movement; based on the position of the equivalent viscosity of the oil within the preset viscosity value range, the oil viscosity grade of the damping state of the hydraulic medium movement is determined.

[0085] The viscosity range is divided according to the range of kinematic viscosity change of the hydraulic medium under different oil temperature and pressure conditions of the engine. For example, the viscosity threshold range is set as the first threshold, the second threshold and the third threshold to form multiple damping state level ranges.

[0086] For example, when the equivalent viscosity of the engine oil is less than the first threshold, it is determined to be a low damping state; when the equivalent viscosity of the engine oil is between the first threshold and the second threshold, it is determined to be a medium-low damping state; when the equivalent viscosity of the engine oil is between the second threshold and the third threshold, it is determined to be a medium-high damping state; when the equivalent viscosity of the engine oil is greater than the third threshold, it is determined to be a high damping state. The first threshold, the second threshold, and the third threshold are exemplary set values, which can be 20 mm² / s, 40 mm² / s, and 60 mm² / s respectively, to reflect the graded differences in motion damping characteristics during the change of the hydraulic medium from a low-temperature thin state to a high-temperature high-viscosity state.

[0087] Based on the oil viscosity grade, the corresponding basic correction gain is read from the damping correction mapping relationship to characterize the degree of influence of changes in the physical properties of the hydraulic medium on the dynamic response sensitivity of oil pressure regulation.

[0088] Furthermore, the process of constructing the damping correction mapping relationship is as follows: During the engine bench or vehicle calibration stage, dynamic response information during the main oil passage pressure regulation process is collected under different oil temperature, speed, and load conditions. Response characteristics such as pressure rise time, pressure overshoot, and steady-state error are recorded under each condition. Simultaneously, based on the equivalent viscosity of the engine oil obtained under the corresponding conditions, sample-level correlation analysis is performed on the pressure regulation response characteristics. The equivalent viscosity of the engine oil is then segmented and statistically analyzed according to viscosity threshold ranges to obtain the average response characteristics under different hydraulic medium motion damping state levels. Based on this, according to the pressure regulation response differences corresponding to each damping state level, the gain correction ratio used to compensate for response hysteresis or overshoot is determined. The hydraulic medium motion damping state level and the corresponding basic correction gain are stored in a one-to-one correspondence to form the damping correction mapping relationship.

[0089] Based on the change trend of the equivalent viscosity of the engine oil relative to the motion damping determined in the previous sampling period, the basic control gain and the basic correction gain are fused and adjusted to form the response sensitivity after viscosity correction.

[0090] Specifically, the evolution characteristics of the equivalent viscosity of the engine oil determined in the current control cycle relative to the previous control cycle are monitored to determine the change range of the motion damping state of the hydraulic medium; by correlating and mapping the change range with the equivalent viscosity of the engine oil in the current state, the damping change ratio reflecting the relative degree of damping fluctuation is obtained, and this ratio is used as the motion damping change trend in the current control cycle.

[0091] After obtaining the trend of motion damping change, the trend of motion damping change is used as a weighting factor to dynamically adjust the fusion ratio between the basic control gain and the basic correction gain. For example, when the trend of motion damping change is greater than the exemplary value of 0.15, it is determined that the medium damping is in a period of drastic evolution, and the weight ratio of the basic correction gain is increased so that it occupies a dominant position in the fusion ratio (for example, the weighting coefficient of the basic correction gain is increased to above 0.7) to enhance the system's dynamic compensation capability for viscosity fluctuations.

[0092] When the trend of motion damping change is less than the exemplary value of 0.05, it is determined that the medium damping is in a stable period. The weight ratio of the basic control gain is increased to make the control law return to the standard state (for example, the weighting coefficient of the basic control gain is increased to above 0.8) in order to maintain the steady-state accuracy of pressure regulation.

[0093] When the trend of motion damping changes between the exemplary value of 0.05 and the exemplary value of 0.15, the weight ratio of the basic control gain and the basic correction gain is continuously adjusted by linear interpolation, so that the fusion ratio changes smoothly with the trend of motion damping, realizing the gradual switching of the two sets of gain coefficients on the weight axis, and finally generating the viscosity-corrected response sensitivity.

[0094] The pressure follow-up deviation is calculated by using the response sensitivity after viscosity correction to generate a pressure regulation control quantity. The pressure regulation control quantity is then combined with the duty cycle reference value to obtain the target control duty cycle signal of the solenoid valve.

[0095] Specifically, the pressure follower deviation is guided to a feedback adjustment path, and the response sensitivity is introduced as the feedback adjustment intensity to perform dynamic compensation correction on the pressure follower deviation. During the execution process, the current amplitude of the pressure follower deviation is mapped in real time through the instantaneous gain adjustment path. Combined with the proportional component in the response sensitivity, an instantaneous correction signal matching the pressure deviation intensity is quickly generated to rapidly suppress the instantaneous fluctuation of the pressure deviation.

[0096] The pressure follow-up deviation is continuously observed and state accumulation is processed through the time domain accumulation channel. The small residual deviations left over time are energized and stacked. The amplitude of the stacked state is controlled by the integral component in the response sensitivity to generate a steady-state compensation signal aimed at eliminating static error. The instantaneous correction signal and the steady-state compensation signal are linearly coupled and reconstructed to synthesize a complete pressure regulation control quantity with composite regulation characteristics.

[0097] The pressure regulation control quantity is injected as an adjustment signal into the output waveform of the duty cycle reference value. Through signal superposition and synthesis, the duty cycle reference value is forced to generate a corresponding waveform width drift based on the feedback result of the pressure deviation, and outputs a solenoid valve target control duty cycle signal with self-correction capability.

[0098] Matching the corresponding chatter frequency and chatter amplitude based on the equivalent viscosity of the engine oil includes:

[0099] As the core actuator of a variable displacement pump, the solenoid valve's spool movement is greatly affected by the damping of the hydraulic medium, exhibiting significant hysteresis and static friction. Existing technologies typically use chatter signals with fixed frequency and amplitude for drag reduction. However, under extremely low temperatures (high viscous resistance) or extremely high temperatures (low damping), the fixed pulse energy is insufficient to adapt to the drastic changes in medium damping. This leads to insufficient spool power and sluggish response at low temperatures, while at high temperatures, insufficient damping causes mechanical impact or overshoot, severely impacting the control accuracy of the main oil passage pressure and the lifespan of the hardware. Therefore, this solution converts the equivalent viscosity of the engine oil into a quantified damping characteristic, establishes a dynamic mapping mechanism for chatter parameters, and performs reverse coupling compensation on the frequency and amplitude of the solenoid valve drive signal to counteract the influence of medium damping fluctuations on the spool movement. The specific process is as follows:

[0100] The equivalent viscosity of engine oil is mapped to the viscosity grade of engine oil under the damping state of hydraulic medium motion.

[0101] It should be noted that the equivalent viscosity of the engine oil is segmented and matched according to the preset viscosity threshold range to determine the current engine oil viscosity grade corresponding to the hydraulic medium.

[0102] Based on the oil viscosity grade, the flow damping characteristic range corresponding to the hydraulic medium is determined, and the corresponding chatter compensation matching rule is selected; adaptive adjustment is performed on the chatter frequency and chatter amplitude in the solenoid valve drive signal so that the chatter frequency and chatter amplitude change in tandem with the change of the flow damping characteristics of the hydraulic medium.

[0103] Specifically, after obtaining the oil viscosity grade, the oil viscosity grade is mapped to the flow damping characteristic range corresponding to the motion damping state of the hydraulic medium to clarify the current flow resistance level and energy attenuation characteristics of the hydraulic medium in the solenoid valve flow channel.

[0104] Based on the differences in the response of the solenoid valve to the high-frequency excitation signal during the opening and closing process under different flow damping characteristics, a chatter compensation matching rule corresponding to the oil viscosity grade is selected to perform adaptive adjustment:

[0105] For low-damping conditions (e.g., when the equivalent viscosity of the engine oil is less than the first threshold, the engine oil temperature is higher than 100°C, and the medium is in a thin state), a "high-frequency, small-amplitude" compensation rule is implemented. Specifically, the flutter frequency is tuned to a higher frequency band (200Hz to 300Hz in the example) while the flutter amplitude is compressed to a smaller range (2% to 3% of the full range in the example). In this state, the high-frequency micro-movement of the solenoid valve core is maintained by using an extremely short switching cycle to prevent mechanical impact of the valve core caused by insufficient medium damping, while eliminating the influence of static friction on the adjustment sensitivity.

[0106] For low to medium damping conditions (e.g., the equivalent viscosity of the engine oil is between the first and second thresholds, and the engine oil temperature is between 80°C and 100°C), a compensation rule of "secondary high frequency and smaller amplitude" is implemented. Specifically, the flutter frequency is set in the secondary high frequency range (example value is 180Hz to 220Hz), and the flutter amplitude is set to a smaller range (example value is 3% to 4% of the full range duty cycle). By slightly increasing the pulse energy, the initial increase in medium damping is adapted to ensure the smooth movement of the valve core when lubrication conditions change.

[0107] For medium-to-high damping conditions (e.g., standard warm-up conditions where the equivalent viscosity of the engine oil is between the second and third thresholds and the engine oil temperature is between 40°C and 80°C), a "balanced response" compensation rule is applied. Specifically, the flutter frequency and flutter amplitude are maintained at intermediate reference levels (example frequency is 150Hz, example amplitude is 5% of the full duty cycle) to balance the power consumption control and response consistency of the solenoid valve, ensuring stable regulation characteristics within the standard flow damping characteristic range.

[0108] For high-damping conditions (e.g., when the equivalent viscosity of the engine oil is greater than the third threshold, the engine oil temperature is below 40°C, and the medium exhibits a high-viscosity state), a "low-frequency, high-amplitude" compensation rule is implemented. Specifically, the chatter frequency is significantly reduced (example values ​​are 80Hz to 100Hz), and the chatter amplitude is simultaneously increased (example values ​​are 8% to 12% of the full-scale duty cycle). In this state, by extending the duration of a single pulse and enhancing the peak energy intensity of the pulse, sufficient impact kinetic energy is generated to overcome the high-viscosity resistance caused by the viscous engine oil coating, forcibly inducing the valve core to produce the expected slight displacement, thereby offsetting the hysteresis effect of the dramatic increase in hydraulic medium damping on the opening and closing response speed of the solenoid valve.

[0109] By using this reverse coupling between the direction of the chatter frequency change (frequency increase when low resistance, frequency decrease when high resistance) and the amplitude change of the chatter value (amplitude decrease when low resistance, amplitude expansion when high resistance), the solenoid valve can maintain a nearly constant dynamic response characteristic under all temperature and viscosity conditions.

[0110] The combined adjustment of the flutter frequency and flutter amplitude is quantized to generate the target flutter frequency and target flutter amplitude for the current control cycle.

[0111] Specifically, the continuously changing dither frequency and dither amplitude are converted into discrete control parameters that can be directly recognized by the solenoid valve drive circuit. During the processing, the reference clock resolution of the solenoid valve control interface (1MHz in the example) is retrieved, and the periodic characteristics of the dither frequency are converted. By mapping the frequency period to a specific number of clock pulses, the abstract frequency requirement is converted into a specific pulse width counting parameter, thereby establishing the high-frequency switching step size of the solenoid valve in the time domain.

[0112] For chatter amplitude, amplitude matching and proportional alignment are performed, mapping the physical value of the chatter amplitude to the effective duty cycle range of the solenoid valve drive command, for example, to a narrow band range of 2% to 12% of the full duty cycle range. Specifically, by calibrating the peak and trough potentials of the chatter waveform, using the target control duty cycle signal of the solenoid valve as the central reference, the target chatter amplitude is divided into symmetrical upper and lower potential biases. This locks the peak potential at "reference level + bias" and the trough potential at "reference level - bias", thus maintaining physical consistency and amplitude alignment between the chatter amplitude and the dynamic fluctuation range of the solenoid valve drive signal.

[0113] By limiting the distribution weight of amplitude in the linear operating range of the solenoid valve, for example, setting the duty cycle fluctuation weight caused by a single chatter to be no higher than 10% of the main duty cycle command, it is ensured that the generated chatter energy is sufficient to induce the valve core to generate high-frequency micro-motion mechanical self-excitation, but will not cause the solenoid valve core displacement to cross the dead zone due to energy overload, thereby avoiding the solenoid valve from generating unexpected full opening and closing actions. Finally, the target chatter frequency and target chatter amplitude are accurately determined in the discrete dimension.

[0114] The equivalent viscosity is converted into a viscosity grade, and an inverse coupling adaptive adjustment of frequency and amplitude is implemented (i.e., "frequency increase and amplitude reduction at low resistance, frequency decrease and amplitude expansion at high resistance"). Under high-damping conditions, the impact kinetic energy generated by enhancing the pulse peak energy overcomes the constraint of viscous oil, forcibly inducing the valve core to move slightly; under low-damping conditions, high-frequency switching maintains the adjustment sensitivity and suppresses mechanical impact. This precision compensation mechanism offsets the influence of medium damping fluctuations on the actuator, enabling the solenoid valve to maintain constant quasi-linear dynamic characteristics across the entire temperature range, achieving millisecond-level precise tracking of the main oil passage pressure.

[0115] Methods for generating solenoid valve drive control commands include:

[0116] A waveform sequence signal with a corresponding period is generated based on the target flutter frequency, and the amplitude of the waveform sequence signal is adjusted using the target flutter amplitude to obtain a duty cycle compensation signal.

[0117] Specifically, a timer generator is used as a clock reference source, and a hardware count value is set according to the received target dither frequency, so that the output terminal generates a high-low level alternating waveform with a constant period; the high-low level alternating waveform presents as a symmetrically distributed square wave or triangular wave sequence on the time axis, which constitutes the frequency skeleton of dither adjustment.

[0118] The original normalized amplitude of the alternating high and low level waveform is guided to the gain adjustment path and coupled with the target jitter amplitude. In this process, the target jitter amplitude serves as an envelope control quantity, directly constraining the oscillation range of the waveform sequence in the vertical dimension. By dynamically adjusting the potential span between high and low levels, the peak-to-peak value of the waveform sequence is precisely aligned with the physical intensity required by the target jitter amplitude. This transforms the original frequency sequence into a duty cycle compensation signal with a specific energy density, characterizing the instantaneous high-frequency impact kinetic energy required to overcome the static friction of the solenoid valve.

[0119] The duty cycle compensation signal and the target control duty cycle signal of the solenoid valve are logically synthesized to generate a pulse width modulation form of solenoid valve drive control command.

[0120] Specifically, the target control duty cycle signal of the solenoid valve is used as the DC component reference, while the generated duty cycle compensation signal is used as the AC disturbance component, both of which are introduced into the signal synthesis path. During the synthesis process, the duty cycle compensation signal, with its inherent high-frequency characteristics, envelope modulates the amplitude of the target control duty cycle signal of the solenoid valve, causing the originally smooth duty cycle reference signal to generate peaks and troughs that fluctuate synchronously with the chatter waveform on the time axis. This superposition is not a simple numerical addition, but rather a waveform coupling process that allows the final control signal to maintain the basic adjustment level while carrying high-frequency micro-vibration characteristics sufficient to overcome the static friction of the valve core and hydraulic resistance. Thus, at the physical output level, it manifests as a composite waveform signal oscillating around the basic duty cycle.

[0121] The composite waveform signal is directed to a pulse width modulation (PWM) interface as a real-time update source for the square wave duty cycle. Within each modulation cycle, the interface dynamically adjusts the on-pulse width and off-pulse interval of the square wave based on the instantaneous amplitude of the composite signal. When the composite signal is at a dithering peak, the conduction time of the square wave is correspondingly extended; when it is at a dithering trough, the conduction time is correspondingly shortened. Through this rapid pulse width modulation, the amplitude characteristics of the composite signal are completely mapped to the duty cycle variation trend of the square wave sequence, thereby generating a pulse width modulation command carrying high-frequency dithering characteristics. This command is ultimately used to drive the on / off operation of the power switching device, achieving precise control of the solenoid valve coil current.

[0122] As feedback signals and to update engine operating condition information, the following are included:

[0123] The solenoid valve drive control command is converted into a power command and a drive current is output to the solenoid valve coil to drive the solenoid valve to act and regulate the amount of oil entering the control chamber of the variable displacement oil pump.

[0124] Specifically, the logic level of the solenoid valve drive control command is converted into a power command with driving capability using a power drive circuit. By adjusting the on / off time of the power transistor, a drive current is output to the solenoid valve coil. The electromagnetic force generated by the solenoid valve coil is used to overcome mechanical resistance and drive the solenoid valve to move. By changing the opening of the solenoid valve, the amount of oil entering the control chamber of the variable displacement oil pump is adjusted, thereby realizing dynamic intervention on the displacement of the variable displacement oil pump.

[0125] Collect the physical variables corresponding to the oil pressure in the main oil passage and convert them into feedback signals in the form of electrical signals;

[0126] The feedback signal is converted into a digital form of feedback pressure value, and the feedback pressure value is used to perform real-time updates on engine operating condition information.

[0127] Specifically, a pressure sensor is used to collect the physical variable corresponding to the oil pressure in the main oil passage. The pressure value is converted into an electrical signal in voltage form through the piezoelectric effect inside the sensor, forming a feedback signal. The feedback signal is then transmitted to an analog-to-digital converter, where quantization processing is performed according to the sampling frequency (1kHz in this example) to convert the electrical feedback signal into a digital feedback pressure value. Through bus communication commands, the feedback pressure value is used to overwrite the old pressure value in the engine operating condition information, completing the update of the engine operating condition information and providing a real-time data basis for the next control cycle.

[0128] The compensation and correction of the kinematic viscosity reference value by utilizing the deviation between the dynamic evolution characteristics of pressure and the standard pressure rise rate includes:

[0129] The dynamic evolution characteristics of pressure are compared with the standard pressure rise rate to determine the damping deviation ratio, which reflects the degree of deviation in the pressure build-up process.

[0130] The acquired dynamic pressure evolution characteristics are compared synchronously with the pre-stored standard pressure rise rate (example value is 5 bar / s). The deviation trend of the current feedback pressure establishment slope relative to the theoretical calibration slope is extracted on the time axis. By associating the deviation trend with the standard pressure rise rate, the influence of different ranges on the state evaluation is eliminated, and a dimensionless coefficient value is output as the damping deviation ratio that reflects the degree of deviation of the actual pressure establishment process from the standard pressure establishment process.

[0131] It should be noted that the process of obtaining the standard pressure rise rate is as follows: During the engine calibration stage, using standard new engine oil and under the reference temperature (80°C in the example), the pressure response curve of the variable displacement oil pump from the initial oil pressure to the target oil pressure is recorded in the full speed range. The average slope of the curve in the steady-state rise segment is extracted and stored as the standard pressure rise rate.

[0132] Incremental compensation is performed on the kinematic viscosity benchmark value based on the damping deviation ratio to determine the equivalent viscosity of the engine oil.

[0133] Specifically, the process of incremental compensation for the kinematic viscosity reference value based on the damping deviation ratio is as follows: Gain scaling mapping is performed on the kinematic viscosity reference value using the damping deviation ratio, ensuring that the resulting viscosity correction increment maintains a linear correlation with the degree of damping deviation. ;in, It is a viscosity correction increment. It is the damping deviation ratio;

[0134] The corresponding viscosity correction increment is generated through incremental compensation processing to characterize the viscosity drift caused by oil shear thinning or thermal oxidation. The correction increment reflecting the viscosity drift characteristics is injected into the kinematic viscosity reference value through signal superposition synthesis, so that the two are merged at the same time scale, thereby outputting the fused equivalent viscosity of the oil.

[0135] Determining the trend of motion damping changes includes:

[0136] Based on the evolution trend of the equivalent viscosity of the oil in the current control cycle and the previous control cycle, the change range of the hydraulic medium motion damping state is determined.

[0137] Specifically, the equivalent viscosity of the oil identified in the current control cycle is compared with the equivalent viscosity of the oil in the previous control cycle on the time axis. The evolution deviation displacement of the equivalent viscosity of the oil between adjacent cycles is extracted, thereby capturing the dynamic evolution value of the physical properties of the hydraulic medium on the time series as the change amplitude of the hydraulic medium motion damping state.

[0138] The change range is correlated with the equivalent viscosity of the engine oil in the current control cycle to obtain a dimensionless damping change ratio, which is then used as the trend of motion damping change within the current control cycle.

[0139] Specifically, the amplitude of the change in the motion damping state of the hydraulic medium is extracted, and the directional attribute of the value is removed to retain its pure fluctuation intensity. The amplitude of the change in the motion damping state of the hydraulic medium after processing is proportionally quantified relative to the equivalent viscosity of the oil in the current control cycle. By eliminating the influence of the amplitude dimension, the relative strength of the damping fluctuation is characterized, and a dimensionless damping change ratio is obtained. This damping change ratio is used as the motion damping change trend in the current control cycle.

[0140] In summary, this invention achieves deep coupling between control logic and the physical properties of hydraulic media by: real-time acquisition of multi-dimensional engine operating parameters; online identification of oil equivalent viscosity using main oil passage pressure change characteristics and oil temperature; and dynamic correction of PID control gain and the frequency and amplitude of solenoid valve chatter signals. This is used in the precise adjustment process of variable displacement oil pumps to eliminate the hysteresis effect and response delay of solenoid valves under different viscosity media and automatically compensate for changes in system motion damping. Throughout the entire temperature range and the entire oil lifespan, it ensures that main oil passage pressure tracking is fast, accurate, stable, and reliable, improving engine lubrication consistency and fuel economy.

[0141] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An electromagnetic valve closed loop control system for an engine variable displacement oil pump characterized by, include: The data acquisition module obtains the engine operating status and hydraulic medium status, and outputs engine operating condition information. The identification module matches the corresponding target oil pressure based on engine operating condition information; The equivalent viscosity of the oil is determined by the dynamic evolution characteristics of the oil temperature and pressure in the hydraulic medium state, and reference information for oil pressure regulation and control is generated. The duty cycle adjustment module, based on the oil pressure regulation control reference information, dynamically adjusts the response sensitivity of the pressure regulation circuit with the equivalent viscosity of the engine oil to adapt to the motion damping changes of the hydraulic medium under different temperature conditions, and obtains the target control duty cycle signal of the solenoid valve. The flutter superposition module matches the corresponding flutter frequency and flutter amplitude based on the equivalent viscosity of the engine oil, and loads the flutter frequency and flutter amplitude onto the target control duty cycle signal of the solenoid valve to generate the solenoid valve drive control command. The drive feedback module drives the solenoid valve to operate according to the solenoid valve drive control command, adjusts the amount of oil entering the control chamber of the variable displacement oil pump, and collects the oil pressure in the main oil passage as a feedback signal to update the engine operating condition information. The method for generating oil pressure regulation and control reference information includes: Extract feedback pressure values ​​according to the sampling period and obtain the dynamic evolution characteristics of pressure at the current sampling time relative to the previous sampling time; The kinematic viscosity reference value is determined based on the real-time oil temperature signal, and the kinematic viscosity reference value is compensated and corrected by the deviation between the dynamic pressure evolution characteristics and the standard pressure rise rate, so as to obtain the equivalent viscosity of the oil. Logically correlate and encapsulate the equivalent viscosity of engine oil with the target engine oil pressure to output oil pressure regulation and control reference information. The method for obtaining the target control duty cycle signal of the solenoid valve includes: Determine the pressure follow-up deviation between the target oil pressure and the feedback pressure value in the oil pressure regulation control reference information; The initial regulation parameters of the pressure regulation loop are obtained as the basic control gain; the basic correction gain is determined based on the equivalent viscosity of the engine oil to determine the motion damping state of the hydraulic medium. Based on the change trend of the equivalent viscosity of the engine oil relative to the motion damping determined in the previous sampling period, the basic control gain and the basic correction gain are fused and adjusted to form the response sensitivity after viscosity correction. The pressure follow-up deviation is calculated by using the response sensitivity after viscosity correction to generate a pressure regulation control quantity. The pressure regulation control quantity is then combined with the duty cycle reference value to obtain the target control duty cycle signal of the solenoid valve.

2. The solenoid valve closed loop control system for an engine variable displacement oil pump of claim 1 wherein, The method for outputting engine operating condition information includes: The system acquires crankshaft speed and throttle opening during engine operation, as well as feedback pressure and real-time oil temperature signals in the hydraulic medium. It then performs voltage regulation and low-pass filtering to output a smooth DC level signal. The smoothed DC level signal is converted into a digital discrete signal, and the digital discrete signal is restored to a physical quantity representation signal. After signal fusion, the engine operating condition information is output.

3. The solenoid valve closed loop control system for an engine variable displacement oil pump of claim 2 wherein, The target oil pressure matched based on engine operating condition information includes: The crankshaft speed and throttle opening in the engine operating information are used as horizontal and vertical axis indices respectively to locate the preset target pressure logic matrix, and the basic target pressure value is output. The target pressure compensation gain is determined based on the crankshaft speed, and the temperature difference characteristics between the real-time oil temperature signal and the reference temperature are obtained. The temperature difference characteristics are then quantized and mapped based on the target pressure compensation gain to obtain the pressure correction amount. The pressure correction amount is then coupled with the base target pressure value to determine the target oil pressure.

4. The solenoid valve closed loop control system for an engine variable displacement oil pump of claim 1 wherein, The matching of the corresponding chatter frequency and chatter amplitude based on the equivalent viscosity of the engine oil includes: The equivalent viscosity of engine oil is mapped to the viscosity grade of engine oil under the damping state of hydraulic medium motion; The flow damping characteristic range of the hydraulic medium is determined based on the oil viscosity grade, and the corresponding chatter compensation matching rule is selected; the chatter frequency and chatter amplitude in the solenoid valve drive signal are adaptively adjusted so that the chatter frequency and chatter amplitude change in tandem with the change of the flow damping characteristics of the hydraulic medium. The combined adjustment of the flutter frequency and flutter amplitude is quantized to generate the target flutter frequency and target flutter amplitude for the current control cycle.

5. The solenoid valve closed loop control system for an engine variable displacement oil pump of claim 4 wherein, The method for generating solenoid valve drive control commands includes: A waveform sequence signal with a corresponding period is generated based on the target flutter frequency, and the amplitude of the waveform sequence signal is adjusted using the target flutter amplitude to obtain a duty cycle compensation signal. The duty cycle compensation signal and the target control duty cycle signal of the solenoid valve are logically synthesized to generate a pulse width modulation form of solenoid valve drive control command.

6. The solenoid valve closed-loop control system for the variable displacement oil pump of an engine as described in claim 5, characterized in that, The step of using feedback signals to update engine operating condition information includes: The solenoid valve drive control command is converted into a power command and the drive current is output to the solenoid valve coil to drive the solenoid valve to act and regulate the amount of oil entering the control chamber of the variable displacement oil pump. Collect the physical variables corresponding to the oil pressure in the main oil passage and convert them into feedback signals in the form of electrical signals; The feedback signal is converted into a digital form of feedback pressure value, and the feedback pressure value is used to perform real-time updates on engine operating condition information.

7. The solenoid valve closed-loop control system for the variable displacement oil pump of an engine as described in claim 1, characterized in that, The method of compensating for and correcting the kinematic viscosity benchmark value by utilizing the deviation between the dynamic evolution characteristics of pressure and the standard pressure rise rate includes: The dynamic evolution characteristics of pressure are compared with the standard pressure rise rate to determine the damping deviation ratio, which reflects the degree of deviation in the pressure build-up process. Incremental compensation is performed on the kinematic viscosity benchmark value based on the damping deviation ratio to determine the equivalent viscosity of the engine oil.

8. The solenoid valve closed-loop control system for the variable displacement oil pump of an engine as described in claim 1, characterized in that, The determination of the trend of motion damping variation includes: Based on the evolution trend of the equivalent viscosity of the oil in the current control cycle and the previous control cycle, determine the change range of the hydraulic medium motion damping state. The change range is correlated with the equivalent viscosity of the engine oil in the current control cycle to obtain a dimensionless damping change ratio, which is then used as the trend of motion damping change in the current control cycle.

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