Compressor compensation pump injection volume self-adaptive control method based on closed-loop feedback

Abstract

The present application belongs to the technical field of intelligent control, and particularly relates to a compressor compensation pump oil injection amount self-adaptive control method based on closed-loop feedback, which comprises the following steps: obtaining the crank angle, oil pressure and oil temperature in each operating cycle of the compressor; calculating the pressure building lag of the current operating cycle; obtaining the oil pressure sub-sequence data in the middle stable section of the suction stroke to calculate the leakage pressure drop gradient; weighting and fusing the theoretical reference single-cycle oil injection amount, the pressure building lag and the leakage degradation index to calculate the compensation increment, and superimposing the compensation increment to the target compensation oil injection amount of the previous operating cycle to generate a control electrical signal to drive the servo driver. The present application overcomes the defect that the traditional fixed control cannot adapt to the gradual change of working conditions, and realizes the dynamic tracking of the compensation oil injection amount.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology. More specifically, this invention relates to an adaptive control method for compressor compensation pump oil injection quantity based on closed-loop feedback. Background Technology

[0002] Compressors are widely used in petrochemical, nuclear power, and high-purity gas compression fields due to their large compression ratio, good sealing performance, and gas uncontaminated by lubricating oil. During compressor operation, the compensation pump replenishes lubricating oil into the cylinder at regular intervals and in measured amounts to compensate for oil leakage from the piston ring gap, thereby ensuring that the diaphragm can tightly adhere to the cylinder head surface at the end of the compression stroke to completely discharge the compressed medium. Normal lubricating oil pressure and appropriate replenishment oil amount are the key foundation for ensuring normal compressor operation and extending service life.

[0003] Currently, existing compressor compensation pumps typically employ a mechanical fixed displacement structure. The eccentric sleeve at the front end of the crankshaft drives the plunger to reciprocate for oil replenishment. When the amount of lubricating oil added to the cylinder exceeds the actual leakage, the excess lubricating oil is discharged through the pressure regulating valve back to the oil sump in the machine body to maintain the maximum pressure limit of the lubricating oil in the cylinder.

[0004] During long-term operation of the compressor under varying operating conditions, the temperature changes of the lubricating oil cause nonlinear viscosity fluctuations. Furthermore, as the equipment operates for longer periods, the wear of the piston rings and cylinder liners leads to a dynamic and gradual change in internal leakage. Traditional fixed-displacement oil replenishment cannot detect these nonlinear changes in leakage caused by temperature and physical wear in advance, which can easily lead to system response lag. When the oil replenishment is insufficient, it can cause pressure build-up failure, the diaphragm cannot fully conform to the curved surface, thereby reducing volumetric efficiency or even causing dry friction. When the oil replenishment is continuously excessive, the frequent and violent pressure relief by the pressure regulating valve can cause severe overheating of the lubricating oil or a large amount of energy waste. Summary of the Invention

[0005] To address the technical problems of traditional control methods failing to adapt to nonlinear oil temperature fluctuations and gradual piston wear, resulting in insufficient oil replenishment leading to decreased volumetric efficiency, or excessive oil replenishment causing system overheating and energy waste, this invention provides a compressor compensation pump oil injection quantity adaptive control method based on closed-loop feedback. This method includes: acquiring the crank angle, oil pressure, and oil temperature for each compressor operating cycle; for the current operating cycle: calculating the pressure build-up hysteresis based on the deviation between the actual crank angle and the theoretical crank angle when the set reference maximum working oil pressure is first reached, combined with the deviation of the average oil temperature from the optimal working oil temperature; and acquiring the... The system generates a subsequence of oil pressure data during the stable middle section of the intake stroke. Based on the change in oil pressure relative to time in the subsequence, it obtains the leakage pressure drop gradient. The ratio of the leakage pressure drop gradient to the obtained benchmark leakage pressure drop gradient is used as the leakage degradation index. The system weights and fuses the pressure build-up hysteresis and the leakage degradation index to correct the theoretical benchmark single-cycle oil injection amount, obtaining the compensation increment. The system sums the extracted target compensation oil injection amount of the previous operating cycle with the compensation increment to obtain the target compensation oil injection amount of the next operating cycle, and converts it into a control electrical signal to be sent to the servo driver to achieve adaptive control of the oil injection amount.

[0006] This invention addresses the technical shortcomings of traditional fixed displacement compensating pumps, which cannot adapt to nonlinear fluctuations in oil temperature and gradual wear of piston seals. By acquiring crank angle, oil pressure, and oil temperature in real time during the compressor's operating cycle, it calculates the pressure build-up hysteresis from a transient thermodynamic perspective and extracts the leakage degradation index from a steady-state mechanical wear perspective. By weightedly fusing these two characteristics representing fluid and geometric leakage factors, it corrects the theoretical benchmark single-cycle oil injection quantity and outputs the target oil injection quantity through a recursive mode that superimposes the current compensation increment from the previous cycle. This closed-loop scheme achieves on-demand dynamic optimization of the oil injection quantity, preventing both the decrease in volumetric efficiency caused by insufficient oil replenishment and the energy waste caused by excessive oil replenishment, thereby improving the stability of compressor operation.

[0007] Preferably, the pressure hysteresis satisfies the expression: In the formula, The built-in hysteresis for the current operating cycle; This refers to the actual crank angle when the set maximum working oil pressure is first reached within the current operating cycle; Theoretical crank angle; This refers to the total crank angle amplitude; This is the average oil temperature during the current operating cycle; The optimal operating oil temperature; It is a natural exponential function.

[0008] This invention introduces an exponential decay factor based on Reynolds viscosity-temperature characteristics, which nonlinearly weights the apparent volume loss with the fluid viscosity reduction mechanism, avoiding the limitations of single phase deviation assessment and enabling more accurate acquisition of transient pressure build-up resistance.

[0009] Preferably, obtaining the oil pressure data subsequence in the middle stable segment of the intake stroke includes: calculating the absolute value of the second derivative of each oil pressure relative to its crank angle in the intake stroke of the current operating cycle, and constructing a second derivative sequence; multiplying the maximum value of the second derivative sequence by a preset stability coefficient to obtain a stability determination threshold; identifying all crank angle segments where the absolute value of the second derivative is continuously less than the stability determination threshold; selecting the crank angle segment with the largest difference between the start and end crank angles, and using its corresponding oil pressure data as the oil pressure data subsequence in the middle stable segment of the intake stroke.

[0010] This invention determines the stability threshold by constructing a second derivative sequence of oil pressure relative to crank angle, effectively filtering out high-frequency electrical noise and pulsation interference caused by micro-vibration of the engine body, and avoiding the risk of misjudging the nonlinear abrupt change segment in the early stage of intake due to excessive tolerance, thereby accurately extracting the linear fallback period data constrained by the internal mechanical seal gap.

[0011] Preferably, obtaining the leakage pressure reduction gradient includes: calculating the first-order differential derivative of each oil pressure in the oil pressure data subsequence with respect to its time, using the absolute value of the first-order differential derivative as the rate of decrease of each oil pressure; and using the mean of all oil pressure decrease rates in the oil pressure data subsequence as the leakage pressure reduction gradient.

[0012] This invention uses the first-order differential derivative to calculate the average velocity amplitude of the natural decline of oil pressure during the steady intake phase, mapping the macroscopic manifestation of the oil pressure decline rate to the microscopic situation of reverse leakage of fluid through wear gaps such as piston rings.

[0013] Preferably, the method for obtaining the benchmark leakage pressure reduction gradient includes: extracting the average leakage pressure reduction gradient during all operating cycles of the compressor test phase as the benchmark leakage pressure reduction gradient.

[0014] Preferably, the theoretical benchmark single-cycle oil injection volume is obtained by multiplying the single piston displacement in the compressor's factory design parameters with the inherent clearance leakage coefficient under calibration conditions.

[0015] Preferably, the compensation increment satisfies the expression: In the formula, This is the incremental compensation for the current operating cycle; This is the theoretical baseline for single-cycle oil injection volume; The built-in hysteresis for the current operating cycle; This represents the leakage degradation index during the current operating cycle. It is the natural logarithm function.

[0016] This invention introduces a natural logarithmic function to perform a polarity mapping on the leakage degradation index, and adds it to the pressure build-up hysteresis, which represents the transient thermodynamic volume deviation. This achieves the linear superposition of volume deviations caused by two different physical causes: gradual mechanical wear and short-term operating disturbances. Through logarithmic transformation, a compensation deviation rate with positive and negative attributes can be output, thereby completing the adaptive matching of the target compensation oil injection quantity.

[0017] Preferably, the target compensation oil injection amount of the previous operating cycle is obtained by extracting the target compensation oil injection amount of the compensation pump output of the previous operating cycle recorded in the actuator feedback register of the control system, and using it as the target compensation oil injection amount of the previous operating cycle.

[0018] Preferably, the conversion to control electrical signals includes: dividing the target compensation oil injection amount for the next operating cycle by the known fixed cross-sectional area of ​​the plunger in the compensation pump to obtain the target effective stroke length of the compensation pump plunger; multiplying the target effective stroke length by the calibrated displacement pulse equivalent of the drive motor to convert it into the total number of target digital pulses that the driver needs to receive; and the microprocessor of the control system generating a corresponding number of control electrical signals based on the total number of target digital pulses.

[0019] Preferably, the method further includes: if the target compensation oil injection amount for the next operating cycle exceeds the maximum oil injection amount of the compressor, immediately interrupting the oil replenishment operation and sending an alarm signal.

[0020] The beneficial effects of this invention are as follows: This invention integrates transient fluid viscosity leakage caused by temperature disturbances with steady-state clearance degradation caused by seal aging. It adopts a recursive mode that superimposes the target compensation oil injection amount of the previous operating cycle with the compensation increment of the current operating cycle. This adaptive control can not only smoothly track the long-term macro aging trajectory of the equipment, but also make flexible adjustments to increase or decrease the amount of oil injection when there are drastic changes in local operating conditions. This solves the passive and lagging situation of traditional control, ensures the stable operation of the compressor, and significantly reduces energy waste. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the adaptive control method for compressor compensation pump oil injection quantity based on closed-loop feedback in this invention; Figure 2 This is a schematic diagram illustrating the evolution of the physical characteristics of the input end of the control algorithm of the present invention. Figure 3 This is a schematic diagram showing the comparison curves of target compensation oil injection volume between conventional control and the adaptive control of this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0024] This invention discloses an adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback, referring to... Figure 1 This includes steps S1 to S4: S1. Obtain the crank angle, oil pressure, and oil temperature of the compressor during each operating cycle.

[0025] It should be noted that the compressor relies on the crankshaft connecting rod mechanism to drive the piston to reciprocate, thereby driving the hydraulic oil to force the diaphragm to vibrate and compress the gas. A complete crankshaft rotation cycle includes three core fluid dynamic stages: intake, compression, and exhaust. In order to accurately capture the leakage situation inside the cylinder and the influence of temperature on fluid characteristics, it is necessary to acquire high-frequency state data that is highly synchronized with time or phase in real time, so as to provide a data foundation for subsequent adaptive control.

[0026] Specifically, a high-precision absolute rotary encoder is installed at the crankshaft end of the compressor to obtain the real-time crank angle; a dynamic pressure transmitter is installed on the cylinder side of the cylinder block component to obtain the real-time lubricating oil pressure; and a temperature sensor is installed at key parts of the oil supply line to obtain the real-time lubricating oil temperature. The sampling frequency of the preset data acquisition system is 1000Hz, and one revolution of the crankshaft is defined as one operating cycle. The implementers can adjust it based on the actual working conditions. In each operating cycle, the real-time crank angle, oil pressure, and oil temperature are synchronously collected and recorded, and the above data are transmitted to the microprocessor of the control system in real time for caching.

[0027] At this point, the crank angle, oil pressure, and oil temperature for each operating cycle are obtained.

[0028] S2. For the current operating cycle: Calculate the pressure build-up hysteresis based on the deviation between the actual crank angle and the theoretical crank angle when the set maximum working oil pressure is first reached, and in combination with the deviation of the average oil temperature from the optimal working oil temperature.

[0029] It should be noted that during the compression stroke of the compressor, as the piston advances, the volume inside the cylinder continuously decreases, and the oil pressure rises rapidly to push the diaphragm to compress the gas. Under ideal leak-free conditions, the crank angle phase at which the oil pressure reaches the predetermined peak value is fixed. However, in actual operation, the gap between the piston ring and the cylinder liner inevitably leads to instantaneous leakage of lubricating oil. According to Poiseuille's law for gap flow in fluid mechanics, the leakage flow rate is inversely proportional to the dynamic viscosity of the lubricating oil. At the same time, based on the Reynolds viscosity-temperature equation, the dynamic viscosity of the lubricating oil decreases exponentially with increasing temperature. A small increase in temperature will cause a sharp drop in viscosity, resulting in an exponential amplification of the leakage, which directly leads to a slower rate of pressure accumulation in the cylinder and a delayed pressure build-up phase. In order to accurately evaluate the dynamic pressure build-up resistance of each cycle, it is not possible to rely solely on the single crank angle phase deviation. It is necessary to introduce an exponential correction term based on the fluid viscosity-temperature physical mechanism. By using nonlinear multiplicative weighting, the apparent geometric leakage behavior is coupled with the internal cause of fluid physical leakage, thereby obtaining an equivalent pressure build-up hysteresis.

[0030] Specifically, for the current operating cycle, the actual crank angle at the first time the oil pressure reaches the set reference maximum working oil pressure within the operating cycle is traversed in chronological order; the set reference maximum working oil pressure is obtained through the current compressor process setting parameters.

[0031] Based on the relative deviation between the actual crank angle and the theoretical crank angle, and considering the deviation of the average oil temperature during the current operating cycle from the optimal operating oil temperature, the built-in pressure hysteresis of the current operating cycle is calculated; the specific calculation formula is as follows:

[0032] In the formula, The built-in hysteresis for the current operating cycle; This refers to the actual crank angle when the set maximum working oil pressure is first reached within the current operating cycle; Theoretical crank angle; This refers to the total crank angle amplitude; This is the average oil temperature during the current operating cycle; The optimal operating oil temperature; It is a natural exponential function.

[0033] in, This reflects the relative retardation of the actual pressure build-up phase within the current operating cycle. Since there is a definite kinematic mapping between piston displacement and crank angle, the phase retardation essentially characterizes the apparent volumetric loss of the system. A larger ratio indicates that the piston needs to travel a longer effective compression stroke to compensate for the oil volume lost due to gap leakage in order to achieve the same target pressure. This is a fluid viscosity decay correction factor derived from Reynolds viscosity-temperature characteristics. From a microscopic molecular dynamics perspective, when the actual oil temperature is higher than the optimal operating oil temperature, molecular thermal motion intensifies, and the internal friction of the lubricating oil decreases sharply, making it easier for the fluid to pass through the piston ring sealing gap and form internal leakage. In this case, the exponent is greater than 1, amplifying the apparent geometric leakage; conversely, it is equal to or slightly less than 1. In summary, if... The higher the value, the greater the difficulty of transient pressure build-up faced by the system in the current operating cycle, which means that the diaphragm is very likely to be unable to completely adhere to the cylinder head surface in the current operating cycle, affecting the gas exhaust rate.

[0034] It should be added that the theoretical crank angle and total crank angle amplitude are known mechanical physical constants obtained through bench testing at the compressor factory; the optimal operating oil temperature is a constant characterized by the physical properties of the lubricating oil.

[0035] At this point, the built-in hysteresis of each running cycle is obtained.

[0036] S3. Obtain the oil pressure data subsequence in the middle of the steady segment of the intake stroke; based on the change of oil pressure relative to time in the oil pressure data subsequence, obtain the leakage pressure drop gradient; use the ratio of the leakage pressure drop gradient to the obtained baseline leakage pressure drop gradient as the leakage degradation index.

[0037] It should be noted that although pressure build-up hysteresis can reflect short-term anomalies in a single cycle, as heavy machinery, the compressor's crankshaft and connecting rod drive the piston components in the cylinder for a long time, inevitably causing physical wear on the piston rings, cylinder liner surfaces, and various seals. This structural degradation is a long-term, gradual process. During the compressor's intake stroke, the piston retracts, the cylinder volume expands, and the internal pressure is relatively low. Under these conditions, the rate of residual oil pressure decline is mainly constrained by the internal mechanical seal clearance. If wear intensifies and the clearance increases, the oil pressure decline gradient in the non-working phase will become significantly steeper. Therefore, by analyzing the changes in the pressure decline gradient within a specific low-pressure drop range and comparing it with the baseline gradient under healthy conditions, transient operating condition interference can be eliminated, and the true degree of physical degradation of the equipment structure can be assessed.

[0038] Specifically, the oil pressure data subsequence within the stable middle section of the intake stroke in the current operating cycle is extracted. The method for obtaining the stable middle section of the intake stroke is as follows: obtain the continuous oil pressure data sequence of the entire intake stroke during the compressor testing phase, calculate the absolute value of the second derivative of each oil pressure relative to its crank angle in the sequence, construct a second derivative sequence, multiply the maximum value of the second derivative sequence by a preset stability coefficient to obtain a stability judgment threshold; traverse the second derivative sequence to identify all crank angle segments where the absolute value of the second derivative is continuously less than the stability judgment threshold; calculate the difference between the start and end crank angles of each crank angle segment, and select the crank angle segment with the largest difference as the crank angle range of the stable middle section of the intake stroke.

[0039] It should be added that the stability coefficient is used to define the tolerance boundary for determining whether the second derivative is sufficiently stable in order to calculate the stability judgment threshold. Since the maximum value of the second derivative in the intake stroke occurs during the nonlinear abrupt change at the beginning and end of the stroke, and the second derivative in the middle stable period is not absolutely zero, it is mainly affected by the high-frequency electrical noise of the sensor and the micro-vibration of the machine body. According to the typical signal-to-noise ratio characteristics of industrial hydraulic sensors, the amplitude of this steady-state background noise usually accounts for 1% to 10% of the transient extreme value. Therefore, the value range is derived to be between 0.01 and 0.1. In the implementation of this invention, it is taken as 0.05 to ensure that it can filter out the background noise pulsation interference within 5% to prevent the extraction segment from being overly fragmented, and will not misjudge the nonlinear transition segment into the stable segment due to excessive tolerance, thereby accurately extracting the pure linear pressure drop feature. The implementer can adjust it according to the signal-to-noise ratio and sampling frequency requirements of the actual acquisition system.

[0040] Since the second derivative is less than the stability threshold, it means that the first rate of change remains basically constant. The crank angle segment with the largest difference between the start and end crank angles represents the linear fall period with the most stable oil pressure drop rate and the longest duration. This effectively eliminates the severe nonlinear pressure drop in the early stage of intake expansion and the fluid inertial fluctuation interference in the late stage of intake.

[0041] Furthermore, the leakage pressure reduction gradient within the current operating cycle is obtained based on the oil pressure data subsequence. The method of obtaining the gradient is as follows: calculate the first-order differential derivative of each oil pressure value in the oil pressure data subsequence with respect to its time, and take the absolute value of the first-order differential derivative as the oil pressure drop rate of each oil pressure; take the average of all oil pressure drop rates in the oil pressure data subsequence as the leakage pressure reduction gradient within the current operating cycle.

[0042] Among them, the leakage pressure drop gradient reflects the average speed amplitude of the natural drop in oil pressure during the steady section of the intake stroke in the current operating cycle. During the steady section of intake, the theoretical volume expansion rate caused by piston movement is relatively constant. At this time, the rate of oil pressure drop directly reflects the reverse leakage of fluid through the piston ring wear gap. Therefore, the larger the leakage pressure drop gradient value, the worse the fluid pressure holding capacity under low-pressure suction state in the current operating cycle.

[0043] The baseline leakage pressure drop gradient is obtained by acquiring the oil pressure data subsequence in the middle of the intake stroke during each operating cycle of the compressor test phase, as well as the leakage pressure drop gradient in each operating cycle. The average value of the leakage pressure drop gradient in all operating cycles during the test phase is used as the baseline leakage pressure drop gradient.

[0044] Among them, the reference leakage pressure drop gradient reflects the inherent normal pressure drop rate of the compressor under the ideal clearance at the factory.

[0045] The ratio of the leakage pressure reduction gradient within the current operating cycle to the baseline leakage pressure reduction gradient is used as the leakage degradation index within the current operating cycle.

[0046] If the leakage degradation index value is greater than 1 for a long period of time and shows a continuous upward trend, it means that the wear clearance of key sealing friction pairs such as piston rings and cylinder liners has increased significantly during the operating cycle, and there is irreversible physical degradation in the mechanical system. The system needs to provide a higher continuous base oil injection volume to fill this part of the structural leakage loss.

[0047] At this point, the leakage degradation index for each operating cycle is obtained.

[0048] S4. Based on the theoretical benchmark single-cycle oil injection volume, pressure build-up hysteresis, and leakage degradation index, the compensation increment is obtained. The target compensation oil injection volume extracted from the previous operating cycle is summed with the compensation increment to obtain the target compensation oil injection volume for the next operating cycle. This is then converted into a control electrical signal and sent to the servo drive to achieve adaptive control of the oil injection volume.

[0049] It should be noted that the plunger stroke of a traditional compensating pump is fixed and cannot dynamically respond to equipment degradation. To achieve intelligent matching, a variable displacement compensating pump system based on servo drive or frequency conversion speed regulation is introduced. In the volumetric efficiency theory of compressors, although the transient fluid viscosity leakage caused by oil temperature fluctuations and the steady-state clearance leakage caused by mechanical wear such as piston rings have completely different physical causes, they satisfy the principle of linear superposition in terms of the macroscopic result of reducing the effective working volume of the cylinder. At the same time, the degradation of physical equipment is a continuous evolution process. The oil injection volume of the previous cycle actually includes the historical degradation state of the system. If the absolute quantity is recalculated based on a fixed benchmark value every cycle, once the sensor is interfered with by high-frequency noise, it is very easy to cause drastic jumps in the oil injection volume and system oscillations. Therefore, the target oil injection volume of the next cycle is obtained by superimposing the oil injection volume of the previous cycle with the compensation increment of the current cycle. This recursive mode ensures that the compensation oil volume closely follows the slow drift of the physical state.

[0050] Specifically, the target compensation oil injection quantity of the compensation pump output in the previous operating cycle, recorded in the actuator feedback register of the control system, is extracted as the target compensation oil injection quantity of the previous operating cycle. It should be added that if the current operating cycle is the first operating cycle, that is, if the previous operating cycle cannot be obtained, the target compensation oil injection quantity of the compensation pump output in the previous operating cycle is set to 0.

[0051] The theoretical baseline single-cycle oil injection volume is obtained by multiplying the single piston displacement in the compressor's factory design parameters with the inherent clearance leakage coefficient under calibrated conditions. Since the theoretical baseline single-cycle oil injection volume represents the basic fluid volume that the equipment needs to compensate for in each cycle under ideal healthy conditions, it is always an absolutely positive value.

[0052] The built-in pressure hysteresis and leakage degradation index of the current operating cycle are weighted and fused to obtain the compensation deviation rate; the theoretical benchmark single-cycle oil injection volume is corrected based on the compensation deviation rate to obtain the compensation increment within the current operating cycle; the specific calculation formula is as follows:

[0053] In the formula, This is the incremental compensation for the current operating cycle; This is the theoretical baseline for single-cycle oil injection volume; The built-in hysteresis for the current operating cycle; This represents the leakage degradation index during the current operating cycle. It is the natural logarithm function.

[0054] in, This constitutes the compensation deviation rate within the current cycle. If the actual pressure build-up within the current cycle is later than the theoretical pressure, such as due to insufficient oil or high temperature, The result is positive; if the actual pressure build-up in the current cycle is earlier than the theoretical pressure, such as due to excessive oil replenishment or a cold start in the previous operating cycle, It is negative; for the leakage degradation index, it is always a positive number greater than zero, but by introducing the natural logarithm function, the physical polarity is accurately captured and mapped: when equipment wear intensifies, that is... ,at this time The value is positive; however, when the sealing performance is better than the baseline condition, such as after changing to high-viscosity lubricating oil, it leads to... At this time The value is negative; when the baseline state is maintained, that is... hour The value is zero; therefore, by adding the mapped leakage degradation index to the pressure build-up hysteresis, the physical superposition of the transient thermodynamic volume deviation and the gradual mechanical wear volume deviation within the current cycle is achieved. It reflects the compensation increment within the current cycle. It is obtained by multiplying the always positive physical reference volume with the polarized deviation rate. Its physical meaning is the additional oil shortage volume or redundant volume obtained within the current cycle due to the combination of temperature fluctuations and mechanical wear.

[0055] Furthermore, the target compensation oil injection amount of the previous operating cycle is summed with the compensation increment in the current operating cycle to obtain the target compensation oil injection amount of the next operating cycle.

[0056] The target compensation oil injection quantity for the next operating cycle is converted into a corresponding control electrical signal and sent to the servo driver at the moment the current cycle ends, thereby realizing adaptive control of the compensation pump oil injection quantity.

[0057] For example, adjusting the servo motor speed or changing the effective stroke of the plunger via an electromagnetic proportional valve drives the compensating pump to precisely output the required oil volume to maintain the optimal cylinder working pressure. Specifically, the known fixed cross-sectional area of ​​the plunger inside the compensating pump is obtained, and the target compensating oil volume for the next operating cycle is divided by the cross-sectional area to calculate the target effective stroke length that the compensating pump plunger needs to advance in the next operating cycle. The calibration displacement pulse equivalent of the drive motor controller is extracted, and the calculated target effective stroke length is multiplied by the displacement pulse equivalent to obtain the total number of target digital pulses that the driver needs to receive. The microprocessor of the control system generates control electrical signals of corresponding quantity and frequency based on the total number of target digital pulses and sends them to the servo driver at the moment the current operating cycle ends. After receiving the electrical signal, the servo motor rotates precisely according to the number of pulses, driving the eccentric adjustment mechanism or linear push rod to move to the set position, changing the effective compression stroke of the plunger.

[0058] It is important to note that if there is a high probability of severe mechanical damage inside the equipment, such as piston ring breakage, leading to extreme leakage, and the target compensation oil injection amount for the next cycle exceeds the maximum oil injection amount of the compressor, the system will immediately stop the oil replenishment operation, send an alarm signal, and prompt manual shutdown for maintenance, thereby preventing secondary damage to the equipment caused by blindly continuing to replenish oil.

[0059] For example, Figure 2 The graph shows the evolution of the physical characteristics of the input end of the control algorithm of this invention. The horizontal axis represents the compressor operating cycle, the left vertical axis represents the pressure build-up hysteresis, and the right vertical axis represents the leakage degradation index. In the range of 100 to 200 cycles, the graph shows a peak and trough change, which first increases to a positive extreme value and then falls back to a negative extreme value. This indicates that the system is disturbed by oil temperature fluctuations and has experienced a dynamic process of first transient leakage aggravation and then short-term oil quantity redundancy. After 250 cycles, the graph shows a nonlinear gradual increase, which indicates that irreversible long-term structural wear has occurred in mechanical seals such as piston rings.

[0060] Figure 3 The graph shows a comparison of the target compensation oil injection amount between traditional control and the adaptive control of this invention. The horizontal axis represents the compressor operating cycle, and the vertical axis represents the target compensation oil injection amount. The adaptive control of this invention makes a flexible adjustment in the disturbance range of 100 to 200 cycles, first rapidly increasing the oil injection amount and then smoothly decreasing it. After 250 cycles, it shows a slow, fine-tuning accumulation, smoothly tracking the macroscopic aging trajectory of the equipment. Compared with the rigid output of traditional fixed control that ignores changes in operating conditions, this invention achieves dynamic matching of the oil injection amount on demand, avoiding equipment failure and energy waste caused by under-compensation or over-compensation.

Claims

1. A method for adaptive control of compressor compensating pump oil injection quantity based on closed-loop feedback, characterized in that, include: Obtain the crank angle, oil pressure, and oil temperature for each operating cycle of the compressor; For the current operating cycle: Based on the deviation between the actual crank angle and the theoretical crank angle when the set maximum working oil pressure is first reached, and combined with the deviation of the average oil temperature from the optimal working oil temperature, calculate the pressure build-up hysteresis. Satisfies the expression: ； This refers to the actual crank angle when the set maximum working oil pressure is first reached within the current operating cycle; Theoretical crank angle; This refers to the total crank angle amplitude; This is the average oil temperature during the current operating cycle; The optimal operating oil temperature; It is a natural exponential function; Obtain the oil pressure data subsequence in the stable middle section of the intake stroke, including: Calculate the absolute value of the second derivative of each oil pressure relative to its crank angle during the intake stroke of the current operating cycle, and construct a second derivative sequence; multiply the maximum value of the second derivative sequence by a preset stability coefficient to obtain a stability determination threshold; identify all crank angle segments where the absolute value of the second derivative is continuously less than the stability determination threshold; select the crank angle segment with the largest difference between the start and end crank angles, and use its corresponding oil pressure data as the oil pressure data subsequence in the stable middle section of the intake stroke; Based on the change of oil pressure relative to time in the oil pressure data subsequence, the leakage pressure drop gradient is obtained; the ratio of the leakage pressure drop gradient to the obtained baseline leakage pressure drop gradient is used as the leakage degradation index. The pressure build-up hysteresis and the leakage degradation index are weighted and fused to correct the theoretical baseline single-cycle injection volume, resulting in a compensation increment. ,satisfy: ； This is the theoretical baseline for single-cycle oil injection volume; This represents the leakage degradation index during the current operating cycle. It is the natural logarithm function; The target compensation oil injection amount extracted from the previous operating cycle is summed with the compensation increment to obtain the target compensation oil injection amount for the next operating cycle. This is then converted into a control electrical signal and sent to the servo driver to achieve adaptive control of the oil injection amount.

2. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The process of obtaining the leakage pressure drop gradient includes: Calculate the first-order differential derivative of each oil pressure relative to its time in the oil pressure data subsequence, and take the absolute value of the first-order differential derivative as the rate of oil pressure drop for each oil pressure; take the mean of all oil pressure drop rates in the oil pressure data subsequence as the leakage pressure drop gradient.

3. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The method for obtaining the baseline leakage pressure drop gradient includes: The average leakage pressure drop gradient during all operating cycles of the compressor test phase is extracted as the benchmark leakage pressure drop gradient.

4. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The theoretical baseline single-cycle oil injection volume is obtained as follows: It is calculated by multiplying the single piston displacement in the compressor's factory design parameters with the inherent clearance leakage coefficient under calibrated conditions.

5. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The method for obtaining the target compensation oil injection amount for the previous operating cycle is as follows: Extract the target compensation oil injection amount recorded in the actuator feedback register of the control system for the output of the compensation pump in the previous operating cycle, and use it as the target compensation oil injection amount for the previous operating cycle.

6. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The conversion into control electrical signals includes: Divide the target compensation injection amount for the next operating cycle by the known fixed cross-sectional area of ​​the plunger inside the compensation pump to obtain the target effective stroke length of the compensation pump plunger; multiply the target effective stroke length by the calibrated displacement pulse equivalent of the drive motor to convert it into the total number of target digital pulses that the driver needs to receive; the microprocessor of the control system generates a corresponding number of control electrical signals based on the total number of target digital pulses.

7. The adaptive control method for compressor compensating pump oil injection quantity based on closed-loop feedback according to claim 1, characterized in that, The method further includes: If the target compensation oil injection amount for the next operating cycle exceeds the maximum oil injection amount of the compressor, the oil replenishment operation will be immediately interrupted and an alarm signal will be sent.

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