A method for oil injection control of a gas compressor cylinder

Abstract

This invention relates to the field of compressor control technology, and in particular to a method for controlling cylinder oil injection in a gas compressor. The method includes: for each independent lubrication point, acquiring a time sequence of friction parameters via high-frequency sampling within the compressor's complete working cycle; extracting characteristic parameters of the piston rings passing through the top and bottom dead centers via waveform decomposition; inputting these parameters into a preset friction pair wear degradation model to obtain the instantaneous wear rate and comparing it with a reference value to obtain the wear rate deviation; then, combining this with the compressor's operating load, determining the oil injection compensation amount and oil injection advance angle for each lubrication point, and driving the corresponding independent oil injection valve to perform oil injection. This invention achieves real-time perception and independent closed-loop control of single-point lubrication status, accurately identifying local oil circuit blockage and insufficient lubrication, avoiding the false alarms of traditional parallel oil supply, dynamically optimizing the timing and amount of oil injection, reducing abnormal wear of friction pairs such as piston rings and support rings, and improving the operational stability and service life of the gas compressor.

Description

Technical Field

[0001] This invention relates to the technical field of compressor control, and more particularly to a method for controlling oil injection in the cylinder of a gas compressor. Background Technology

[0002] During the operation of a gas compressor, to ensure reliable lubrication between the piston rings and the cylinder surface, a lubricating oil injector is typically used to inject lubricating oil into the cylinder. In existing lubrication systems, to simplify pipeline layout and reduce modification costs, a parallel oil supply method is often adopted. That is, a single oil injection valve of a lubricator supplies oil in parallel to two or more lubrication points on the cylinder body through a three-way or multi-way connector.

[0003] In existing parallel oil supply methods, when one lubrication point malfunctions due to blockage by impurities or poor oil flow, the oil injection valve can still continue to supply oil through other unblocked lubrication points. This causes the oil injector's drip sight glass to show a false indication of normal operation, making it impossible for operators to detect local oil shortage faults in a timely manner through routine inspections. As a result, the piston rings, support rings, and other friction pairs at the corresponding blockage points experience abnormal wear due to long-term insufficient lubrication. The problem is not discovered until obvious abnormalities such as increased equipment vibration and elevated exhaust temperature occur, at which point irreversible damage to core components has often already been caused. Summary of the Invention

[0004] This invention provides a method for controlling oil injection in the cylinder of a gas compressor, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for controlling oil injection in a gas compressor cylinder includes: For each independent lubrication point, within one complete working cycle of the compressor, the time sequence of friction parameters at that independent lubrication point is continuously collected at a sampling rate higher than the piston motion frequency; Waveform decomposition is performed on the time series of friction parameters to extract the feature parameters associated with the piston ring passing through the top dead center and bottom dead center times corresponding to the independent lubrication point; The characteristic parameters are input into the pre-built friction pair wear degradation model, the instantaneous wear rate of the current cycle of the independent lubrication point is output, and it is compared with the preset reference wear rate of the independent lubrication point to obtain the wear rate deviation value. Based on the wear rate deviation value and the current operating load of the gas compressor, determine the oil injection compensation amount and oil injection advance angle for this independent lubrication point; Based on the oil injection compensation amount and the oil injection advance angle, the independent oil injection valve corresponding to the independent lubrication point is controlled to perform the oil injection action.

[0006] Furthermore, the friction parameters include instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous oil injection back pressure.

[0007] Furthermore, waveform decomposition includes: Based on the crankshaft angle signal, the time-domain friction parameter time series is reconstructed into a crankshaft angle domain equal-angle interval series to eliminate phase distortion caused by speed fluctuations.

[0008] Furthermore, the characteristic parameters include the valley of oil film thickness, the peak of temperature, and the abrupt slope of the injection back pressure.

[0009] Furthermore, feature parameters associated with the piston ring passing through top dead center and bottom dead center at the time corresponding to this independent lubrication point are extracted, including: Based on the crankshaft angle signal, the times when the piston rings pass through the top dead center and bottom dead center are determined respectively; The lowest value of the oil film thickness near the top dead center is extracted as the valley feature, and the highest value of the cylinder wall temperature near the bottom dead center is extracted as the peak feature. The maximum slope value at the instant the injection valve opens on the oil injection back pressure curve is extracted as the abrupt change slope feature.

[0010] Furthermore, the friction pair wear degradation model is constructed based on the Achad wear theory. Through multidimensional coupling mapping of oil film thickness valley, cylinder wall temperature peak, and injection back pressure abrupt change slope, the instantaneous wear rate is output.

[0011] Furthermore, the friction pair wear degradation model determines the boundary lubrication contact probability by the oil film thickness valley, corrects the material hardness attenuation coefficient by the cylinder wall temperature peak, and compensates for the wear increment caused by oil supply lag by the slope of the sudden change in oil injection back pressure.

[0012] Furthermore, the amount of oil injection compensation is positively correlated with the wear rate deviation, and an operating load correction coefficient is introduced to increase the compensation gain under high load conditions.

[0013] Furthermore, methods for determining the oil injection advance angle include: When the wear rate deviation is greater than zero, the oil injection advance angle is advanced relative to the standard oil injection phase angle according to the magnitude of the deviation. The advance angle is positively correlated with the deviation value.

[0014] Furthermore, controlling the independent oil injection valve to perform the oil injection action includes: Using the crankshaft rotation angle as the trigger reference, the oil injection valve is activated at the target oil injection trigger angle; The valve opening pulse width is determined based on the oil injection compensation amount, and a driving method combining peak drive and holding current is adopted. After the oil injection is completed, the characteristics of the oil injection back pressure falling edge are collected to determine whether the valve core is stuck or not closed tightly.

[0015] The technical solution of this invention can achieve the following technical effects: By acquiring and analyzing real-time friction parameters of each independent lubrication point at high frequency, an early warning and closed-loop control mechanism based on wear dynamics is constructed. This enables microscopic perception and dynamic quantitative assessment of the lubrication state of friction pairs, elevating wear monitoring from traditional post-event judgment to pre-event rate prediction. Through an algorithm based on crankshaft phase and multi-physics field characteristics, precise oil injection compensation is achieved for each lubrication point, including adaptive optimization of oil quantity and injection phase. Ultimately, a fully closed-loop lubrication system of state perception, wear prediction, and dynamic compensation is constructed, eliminating hidden lubrication failures caused by local blockage of the oil circuit and improving the life of key friction pairs and the overall operational safety of the machine.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of a method for controlling oil injection in a gas compressor cylinder according to the present invention. Figure 2 This is a schematic diagram of the waveform decomposition and feature parameter extraction process in this invention; Figure 3 This is a schematic diagram of the process for calculating the wear rate deviation by inputting the wear degradation model in this invention; Figure 4 This is a schematic diagram of the process for determining the oil injection compensation amount and advance angle in conjunction with the operating load in this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] like Figure 1 As shown, the present invention discloses a method for controlling oil injection in a gas compressor cylinder. The method is applied to an oil injection system with multiple independent oil injection channels, each corresponding to an independent lubrication point on the cylinder. Specifically, it includes the following steps: Step S1: For each independent lubrication point, within one complete working cycle of the compressor, continuously collect the time sequence of friction parameters at that independent lubrication point at a sampling rate higher than the piston movement frequency; Step S2: Perform waveform decomposition on the time sequence of friction parameters and extract the feature parameters associated with the times when the piston ring passes through the top dead center and bottom dead center corresponding to the independent lubrication point; Step S3: Input the feature parameters into the pre-built friction pair wear degradation model, output the instantaneous wear rate of the current cycle of the independent lubrication point, and compare it with the preset reference wear rate of the independent lubrication point to obtain the wear rate deviation value; Step S4: Based on the wear rate deviation value and the current operating load of the gas compressor, determine the oil injection compensation amount and oil injection advance angle for this independent lubrication point; Step S5: Based on the oil injection compensation amount and the oil injection advance angle, control the independent oil injection valve corresponding to the independent lubrication point to perform the oil injection action.

[0022] In this embodiment, by setting an independent oil injection channel for each independent lubrication point and collecting the time sequence of friction parameters in real time, and combining waveform decomposition and wear degradation model to accurately determine the lubrication status of each lubrication point, local oil circuit blockage or insufficient lubrication problems can be identified in real time. This avoids the false impression of a normal dripping sight glass but local oil cut-off that occurs in traditional parallel oil supply, and realizes independent oil injection control and dynamic compensation for a single lubrication point. This reduces abnormal wear of friction pairs such as piston rings and support rings, and improves the operational reliability and service life of the gas compressor.

[0023] In a specific implementation, as one example, given that existing parallel oil supply methods result in minimal changes in total flow rate due to the diversion effect when a single point of blockage occurs, and that conventional macroscopic monitoring methods cannot capture local lubrication failures, it is necessary to extend the monitoring reach from the oil supply end to the oil consumption end, that is, to directly measure the physical quantities at the contact interface between the cylinder inner wall and the piston ring. In this embodiment, instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous oil injection back pressure are selected as friction parameters. By deploying an embedded multidimensional sensor array and adopting a crankshaft angle-triggered sampling strategy, the instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous oil injection back pressure are simultaneously acquired, as detailed below: Step S11: Machine sensor mounting holes within the axial stroke coverage area corresponding to each independent lubrication point of the cylinder, avoiding the positions of the air valve and sealing groove. Embed a high-temperature and high-pressure resistant multidimensional sensor probe in the hole. The probe internally encapsulates a capacitive micro-displacement sensitive element, a thin-film thermocouple array, and a high-frequency dynamic piezoresistive chip. The capacitive element uses lubricating oil as a medium to sense the change in the distance between the plates to characterize the oil film thickness. The thin-film thermocouple uses the Seebeck effect to sense the surface temperature difference caused by frictional heat. The dynamic piezoresistive chip is directly connected to the end of the oil injection pipeline to sense fluid pressure fluctuations. Step S12: Install a photoelectric encoder at the free end of the compressor crankshaft to output a pulse signal that is strictly corresponding to the crankshaft rotation angle in real time. Define the crankshaft rotation angle as the time reference domain for data acquisition, replacing the traditional absolute time reference, so as to eliminate the influence of compressor speed fluctuations on data phase alignment. Step S13: Configure the data acquisition card, receive the rotation pulse of the photoelectric encoder as an external hardware trigger interrupt, set the sampling logic to trigger a parallel reading operation once every fixed rotation interval, and synchronously acquire the analog signals of all independent lubrication point probes and convert them into digital sequences within a complete working cycle, ensuring that the sampling frequency is much higher than the piston reciprocating motion frequency, so as to completely record the transient physical quantity changes of the piston ring at the moment of passing the top dead center and the bottom dead center. Step S14: Preprocess the acquired raw digital sequence to remove outliers caused by electromagnetic interference, and mark the corresponding crankshaft angle index to form a time sequence of friction parameters containing three dimensions: instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous oil injection back pressure.

[0024] In this embodiment, instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous back pressure are selected as friction parameters because they have different and complementary response mechanisms to lubrication failure. Instantaneous oil film thickness directly reflects the fluid lubrication state between the piston ring and the cylinder surface. Oil film rupture is a direct precursor to dry friction. The capacitive measurement principle can respond to microsecond-level thickness changes and capture the phenomenon of local oil film thinning. Cylinder wall temperature reflects the accumulation of frictional heat. When lubrication is insufficient, the contact surface temperature will rise sharply in a very short time. The low thermal inertia of the thin-film thermocouple allows it to follow the temperature pulse when the piston ring sweeps across, providing thermodynamic evidence of wear. Back pressure reflects the patency of the oil passage. Blockage of the oil passage will directly change the fluid dynamics characteristics, causing the back pressure of the injection valve to open momentarily. The pressure build-up slope and steady-state pressure value are distorted. The high-frequency pressure sensor can record this dynamic process, which serves as a direct basis for judging the smoothness of the oil circuit. The combination of these three factors constitutes a complete causal chain from oil supply obstruction to oil film failure and then to thermal damage. In this embodiment, the monitoring point is moved from the oiler outlet to the friction pair interface, and the sampling reference is converted from the time domain to the spatial domain to ensure accurate alignment of feature point data under variable speed conditions. It can identify oil circuit blockage or poor lubrication at a single lubrication point in advance when the oiler sight glass shows normal and the total flow does not change significantly. The instantaneous state of the friction pair is quantified by high-frequency time-series data, providing accurate input variables for calculating the instantaneous wear rate, thereby avoiding abnormal piston ring wear and unplanned equipment shutdown caused by partial oil cut-off.

[0025] In some embodiments of the present invention, the time series of friction parameters is directly acquired based on the time axis. However, due to fluctuations in compressor speed, the key phase points of piston motion are not fixed on the time axis. If extreme value searches are performed directly in the time domain, erroneous data is easily captured due to phase drift, and the high-frequency mechanical vibration noise mixed in the original signal can mask the true lubrication characteristics. Based on these problems, this embodiment constructs a waveform decomposition mechanism based on crankshaft angle domain resampling and phase-locked windows to convert the time-varying signal into an angle domain synchronous signal. Within a specific kinematic window, extreme values ​​and slope features with clear physical meaning are extracted, thereby extracting key characteristic parameters representing lubrication failure, such as… Figure 2 As shown, perform the following operations: Step S21: Receive the real-time rotation angle pulse output by the crankshaft encoder, establish a mapping relationship table between crankshaft rotation angle and sampling time, and use an interpolation algorithm to reconstruct the obtained instantaneous oil film thickness, instantaneous cylinder wall temperature and instantaneous oil injection back pressure time sequence based on the time domain into an equal angle interval sequence based on the crankshaft rotation angle domain, so that the data points in each working cycle are aligned within the rotation angle range of 0 degrees to 720 degrees, and the phase distortion caused by speed fluctuation is eliminated; Step S22: Based on the cylinder geometry, preset the top dead center angle threshold range and the bottom dead center angle threshold range. In the reconstructed angle domain sequence, extract the local data segment corresponding to the piston ring passing through the top dead center as the first feature window, and extract the local data segment corresponding to the piston ring passing through the bottom dead center as the second feature window. At the same time, based on the oil injection valve control timing or the starting point of the pressure waveform, locate the corner position where the oil injection action occurs and extract the third feature window containing the pressure rising edge. Step S23: Within the first feature window, the instantaneous oil film thickness data is traversed and compared, discontinuous abrupt changes caused by high-frequency noise from the sensor are removed, and the data point with the smallest value within the window is selected and its corresponding oil film thickness value is marked as the oil film thickness valley value feature of the current cycle. Step S24: Within the second feature window, the instantaneous cylinder wall temperature data is traversed and compared, the data point with the largest value in the window is identified and extracted, and the corresponding cylinder wall temperature value is marked as the cylinder wall temperature peak feature of the current cycle. Step S25: In the third feature window, calculate the ratio of the difference between adjacent sampling points of instantaneous oil injection back pressure data to the corresponding angle increment, generate a pressure change rate sequence, extract the point with the largest value from the sequence, and mark its corresponding change rate value as the oil injection back pressure sudden change slope feature of the current cycle. Step S26: Encapsulate the extracted oil film thickness valley value, cylinder wall temperature peak value, and oil injection back pressure abrupt change slope as feature parameters, and associate them with the current cycle count and lubrication point number.

[0026] In this embodiment, the idea of ​​using crankshaft angle domain resampling instead of directly using time domain data stems from the fact that the friction and lubrication state of a reciprocating compressor is essentially a function of piston position. When load changes cause speed fluctuations, the timing of the same lubrication event will change accordingly, but its position on the crankshaft angle remains constant. If a fixed window is set directly in the time domain to search for extreme values, the window may deviate from the target phase under variable speed conditions, resulting in the extraction of data from the middle of the piston stroke instead of the dead center data, causing feature distortion. By reconstructing and forcibly aligning all data to a unified angular coordinate system, the phase consistency of feature extraction can be ensured. The oil film thickness valley value is selected for extraction at the top dead center window because the piston's instantaneous velocity is zero at dead center, the hydrodynamic effect disappears, and the oil film thickness reaches the minimum value of the entire cycle. At this point, boundary lubrication or even dry friction is most likely to occur. This valley value is the most sensitive indicator for judging whether anti-wear protection has failed. If the oil film at this point is not broken, other positions are usually safe. The cylinder wall temperature peak value is selected for extraction at the bottom dead center window. This is because the piston rings frequently reverse direction and have a relatively long residence time in the bottom dead center region, making it easy for frictional heat to accumulate. This area is also often a weak point in the lubricant distribution, and the temperature peak directly reflects the trend of thermal damage caused by long-term poor lubrication, serving as a lag verification of the instantaneous oil film state. The selection of extracting the abrupt change slope of the injection back pressure rather than the steady-state pressure is because, under a parallel oil supply architecture, a single-point blockage has a negligible impact on the overall steady-state pressure of the system, but it significantly increases the flow resistance of that branch, causing the pressure build-up process at the moment the injection valve opens to slow down, i.e., the pressure rise slope decreases. This dynamic response characteristic is more sensitive than the steady-state value to reflecting subtle changes in oil circuit patency and can be captured in the early stages of blockage. This embodiment employs a kinematic phase-based angular domain locking extraction strategy, compressing continuous waveform data into several key feature points with clear physical meaning. This eliminates the interference of speed fluctuations on feature extraction accuracy, ensuring that the obtained feature parameters truly correspond to the critical dangerous conditions of piston movement and improving the correlation between the feature vector and the actual wear state of the friction pair.

[0027] In practical implementation, as one example, existing wear assessment methods mostly rely on dimensional measurements after shutdown or empirical estimations based on operating time. They cannot quantify the instantaneous wear state of a single lubrication point under specific operating conditions in real time, and lack a mathematical mechanism to couple and map multi-dimensional physical quantities such as oil film thickness, cylinder wall temperature, and injection back pressure to wear rate, resulting in a lack of feedback basis for the control strategy. This embodiment constructs a friction pair wear degradation model based on multi-physics field coupling, transforms characteristic parameters into instantaneous wear rate through nonlinear mapping relationships, and generates a deviation signal by comparing it with a benchmark value, such as... Figure 3 As shown, the specific implementation steps are as follows: Step S31: Initialize the friction pair wear degradation model. The model has a pre-set multidimensional transfer function based on the Acard wear theory. The input variables are defined as the oil film thickness valley, cylinder wall temperature peak and injection back pressure abrupt change slope. The output variable is defined as the instantaneous wear rate. A calibration coefficient matrix for the current compressor material pairing and lubricant characteristics is loaded into the model. The pre-construction process of the friction pair wear degradation model can be achieved by building a single-cylinder simulation test bench that reproduces the actual compressor motion law and pressure curve, integrating friction parameter sensors and online material loss monitoring devices, and simultaneously collecting the time series of friction parameters and the true value of instantaneous wear rate under the designed full-factor orthogonal test conditions. Subsequently, the data is decomposed into waveforms to extract the oil film thickness valley, cylinder wall temperature peak and injection back pressure abrupt change slope as input features. Combined with the true value of wear rate, a full spectrum dataset is constructed, and a basic physical equation including contact load, material hardness and oil film thickness ratio discriminant function is established based on the Acard wear theory. The boundary lubrication index correction factor is embedded to characterize the wear abrupt change characteristics when the oil film breaks down. Then, the unknown coefficients and nonlinear terms in the physical equation are trained using a regression algorithm, focusing on fitting the critical change of oil film, high-temperature material softening decay and oil supply delay compensation relationship until the prediction error converges to the preset tolerance. Finally, the trained model parameters, weight matrix and correction formula are solidified into digital files to form a callable model library for different material pairs and lubricating oils. Step S32: Normalize the valley value of oil film thickness, the peak value of temperature and the abrupt change slope of oil injection back pressure, eliminate the difference in dimensions, and then input them synchronously into the input layer of the wear degradation model. Step S33: Perform the first-level mapping operation inside the model, calculate the boundary lubrication contact probability using the oil film thickness valley value, and trigger the nonlinear contact stress amplification factor when the oil film thickness valley value is lower than the preset critical safety threshold to simulate the trend of rapid increase in wear caused by direct contact of metal micro-protrusions. Step S34: Perform the second-level mapping operation inside the model, use the peak temperature of the cylinder wall to correct the hardness attenuation coefficient of the material, and dynamically adjust the material resistance parameters in the wear calculation based on the negative correlation between temperature and material yield strength to reflect the physical process of wear accelerated by the high temperature softening effect. Step S35: Perform the third-level mapping operation inside the model, calculate the oil supply adequacy weight using the oil injection back pressure change slope. When the change slope is lower than the standard response slope, it is determined to be oil supply lag or insufficiency. Introduce a time integral term to compensate for the dry friction duration caused by the delay in oil film establishment, and then correct the calculation result of instantaneous wear rate. Step S36: Based on the above three-level mapping calculation results, output the instantaneous wear rate value of the current working cycle of the independent lubrication point through a weighted fusion algorithm; Step S37: Call the reference wear rate obtained from long-term operation statistics of the independent lubrication point under healthy conditions. The reference value corresponds to the average wear level of the compressor under rated load, normal oil temperature and standard oil supply pressure. Perform an algebraic subtraction operation between the instantaneous wear rate and the reference wear rate to obtain the wear rate deviation value. If the deviation value is positive, it indicates that the current wear state is worse than the reference level. If the deviation value is zero or negative, it indicates that the current wear state is normal or better than the reference level.

[0028] In this embodiment, wear is not caused by a single factor, but is the result of the combined effects of lubrication state, material properties, and oil supply dynamics. The model selects the oil film thickness valley as the core input because, according to fluid lubrication theory, when the oil film thickness is less than the sum of surface roughness, the wear rate increases exponentially. This parameter directly determines whether the contact mode is fluid lubrication or boundary / mixed lubrication, and is a decisive factor in wear occurrence. If this parameter is ignored and judgment is based solely on temperature, the response is often delayed until wear has already occurred and a large amount of heat has been generated. The cylinder wall temperature peak is selected as a correction factor because the hardness and strength of the friction pair material decrease with increasing temperature. The same contact stress at high temperatures leads to more severe plastic deformation and material spalling. The model corrects the material resistance parameters by temperature, which can more realistically reflect the accelerated wear phenomenon under high-temperature conditions. The oil injection back pressure abrupt change slope is selected as a dynamic compensation term because, during reciprocating motion, the oil injection... Even minor delays in the piston can cause it to experience a dry friction stroke without an oil film near top dead center. The smaller the slope, the slower the pressure build-up, the more delayed the oil film formation, the longer the dry friction time, and the greater the wear. Introducing this into the model can quantify the additional wear caused by poor oil supply dynamics. This embodiment uses a multi-dimensional coupled mapping model based on physical mechanisms to convert instantaneous physical state quantities into wear rates in real time. It can calculate the actual wear rate of each lubrication point in each working cycle in real time and quantitatively, rather than just judging whether there is an anomaly. By comparing the deviation between the instantaneous value and the reference value, it can identify minor wear deterioration trends. Even before the equipment vibrates or the exhaust temperature is abnormal, it can detect the wear risk caused by lubrication failure in advance. This provides a clear quantitative basis for oil quantity compensation and oil injection phase adjustment, avoiding carbon buildup caused by over-oil injection or damage caused by under-oil injection, and realizing the transformation from post-fault maintenance to wear process control.

[0029] In practical implementation, as one example, existing oil injection control strategies mostly adopt fixed-cycle quantitative injection based on running time or total load, which cannot dynamically respond to the real-time wear state of a single lubrication point. Furthermore, the oil injection phase is usually fixed, meaning that when local lubrication deterioration occurs, simply increasing the oil quantity may fail to establish an effective oil film before the piston reaches the critical friction area due to injection timing lag. Therefore, this embodiment constructs a two-variable decoupled control mechanism, mapping the wear rate deviation value to incremental compensation of the oil injection quantity, and simultaneously mapping the sign and magnitude of the deviation value to a dynamic advance of the oil injection phase. Through coordinated adjustment of quantity and timing, it ensures that the lubricating oil is spread before the piston ring reaches the high-wear-risk area. Figure 4 As shown, the specific implementation steps are as follows: Step S41: Read the current cycle wear rate deviation value and collect the current operating load signal of the gas compressor in real time. The operating load signal includes at least one of the exhaust pressure, intake flow rate or motor current, which is used to characterize the gas load state in the cylinder. Step S42: Determine the sign of the wear rate deviation value. If the deviation value is less than or equal to zero, determine that the independent lubrication point is in a healthy or over-lubricated state, maintain the standard oil injection compensation amount at zero, and keep the standard oil injection advance angle unchanged. If the deviation value is greater than zero, determine that the independent lubrication point has an abnormal wear risk due to insufficient lubrication, and enter the compensation calculation process. Step S43: Construct an oil injection compensation calculation function, with the wear rate deviation value as the first input variable and the current operating load as the second input variable. The oil injection compensation amount is positively correlated with the wear rate deviation value, that is, the larger the deviation value, the more additional oil injection is required. At the same time, an operating load correction coefficient is introduced. When the operating load is higher than the rated load, the gain slope of the compensation amount is increased to counteract the tendency of oil film to break under high load. Calculate the single-cycle oil injection compensation amount for this independent lubrication point. Step S44: Construct a dynamic adjustment function for the oil injection advance angle. With the wear rate deviation value as the only variable, define the standard oil injection phase as the reference zero point. When the wear rate deviation value is greater than zero, calculate a positive angle offset as the oil injection advance angle. This angle offset is positively correlated with the wear rate deviation value. That is, the larger the deviation value, the larger the angle of advance of the oil injection action relative to the crankshaft rotation angle. Step S45: Set the saturation threshold of the oil injection advance angle to prevent the lubricating oil from being sucked into the air valve or causing liquid hammer due to excessive deviation. When the calculated angle offset exceeds the threshold, it is forcibly locked to the maximum allowable advance angle. Step S46: Add the calculated oil injection compensation amount to the base oil injection amount to generate the final target oil injection amount, and add the calculated oil injection advance angle to the standard oil injection crankshaft angle to generate the final target oil injection trigger angle.

[0030] In this embodiment, the lubricating oil requires a certain physical time to form an effective bearing oil film on the cylinder mirror surface from the injection point. This process includes stages such as oil droplet flight, impact on the wall, spreading and diffusion, and being evenly coated by the piston rings. When the wear rate deviation value is greater than zero, it indicates that the current lubrication state is insufficient to resist the wear of the friction pair. This may be due to insufficient absolute supply of lubricating oil or too late injection timing, resulting in the newly injected lubricating oil not having fully spread by the time the piston rings reach top dead center. The larger the wear rate deviation value, the higher the risk of oil film rupture or the slower the oil film reconstruction speed. At this time, not only more oil is needed, but also earlier injection is required so that the lubricating oil has sufficient time to evenly adhere to the cylinder mirror surface under the action of centrifugal force and airflow before the piston rings reach the danger zone. This embodiment directly replenishes the volume of lubricating oil lost due to leakage, consumption, or uneven distribution by increasing the injection compensation amount, ensuring sufficient continuous oil supply. By dynamically advancing the injection angle, the advance of the crankshaft angle is used to exchange for the pre-spreading time of the lubricating oil on the cylinder wall. The operating load is introduced as... The correction factor for the amount of oil injected is due to the higher gas pressure inside the cylinder under high load conditions, which increases the specific pressure of the piston rings against the cylinder wall, making it easier for the oil film to be broken. Therefore, under the same wear deviation, a larger incremental oil injection compensation is required under high load conditions. Setting a saturation threshold for the oil injection advance angle is used to prevent the calculated advance angle from being too large under extreme conditions, which would cause oil injection to occur when the piston does not cover the oil injection hole or the valve is open, thereby reducing the risk of lubricating oil waste or lubricating oil entering the air circuit system. This embodiment adopts closed-loop quantity and time dual-dimensional dynamic control based on real-time wear feedback. The oil injection phase is used as an active variable that is dynamically adjusted according to the wear state. At the moment the wear trend is detected, not only is the oil supply increased, but the spatiotemporal distribution of lubricating oil in the key friction area is optimized by advancing the oil injection timing. This ensures that when the piston rings reach high-risk positions such as top dead center, a complete and appropriately thick oil film has been pre-formed on the cylinder wall surface, thereby achieving the best anti-wear effect with the minimum oil injection cost. This avoids the phenomenon of oil being present but not lubricated in time due to oil injection lag, and suppresses abnormal wear caused by local oil cut-off.

[0031] In practical implementation, as one example, existing oil injection actuators mostly use mechanical metering pumps or fixed-pulse-width solenoid valves for control. Their single oil injection volume depends on the mechanical stroke or fixed opening time, making it impossible to dynamically respond to microsecond-level phase adjustment commands and milligram-level flow compensation requirements within a single work cycle. Furthermore, they lack a closed-loop confirmation mechanism for the actual execution effect of the oil injection action. Therefore, this embodiment constructs an independent oil injection valve execution strategy based on high-precision electromagnetic drive and real-time pulse width modulation, converting the target oil injection volume and target oil injection trigger angle into precise current drive waveforms and timing control signals. The specific implementation steps are as follows: Step S51: Receive the target oil injection trigger angle and target oil injection compensation amount for the independent lubrication point, read the real-time angle count value of the current crankshaft encoder, and immediately generate an oil injection start interrupt signal when the real-time angle count value reaches the target oil injection trigger angle. Step S52: Based on the target oil injection compensation amount, query the pre-calibrated oil injection amount-valve opening time mapping curve. This curve is obtained based on the valve flow characteristic test under different back pressure conditions. Convert the target oil injection compensation amount into the theoretical valve opening time required for the current cycle, and add the compensation time constant required due to the lag in the electromagnet response to obtain the final control pulse width. Step S53: Send a high-level trigger signal to the independent oil injection valve drive circuit corresponding to the independent lubrication point. The drive circuit outputs a peak current to overcome the spring preload and fluid static pressure, so that the valve core completes the displacement from closed to fully open in milliseconds. At the same time, the internal timer is started to measure the opening time. Step S54: During the continuous opening of the valve, the drive circuit maintains the holding current to stabilize the valve core position, reduce coil heating and prevent valve core chatter caused by current fluctuations, ensure a constant cross-section of the lubricating oil flow channel, and guarantee flow linearity. Step S55: When the internal timer count reaches the final control pulse width, the drive circuit immediately cuts off the current or applies a reverse demagnetizing voltage, using the spring reset force and fluid reverse pressure to make the valve core quickly return to its seat and close, terminating the oil injection action. Step S56: Synchronously acquire the feedback signal of the oil injection back pressure sensor at the moment the oil injection valve closes, detect the falling edge slope of the pressure waveform and the steady-state residual pressure. If the falling edge slope is lower than the preset threshold or the residual pressure is abnormal, it is determined that the valve core is stuck or not closed tightly, a fault mark is generated and the current cycle data is recorded. Step S57: Use the actual rotation angle, actual opening duration, and fault marker status of this oil injection action as the historical basis for the control parameter correction of the next cycle, and complete the closed loop of the current cycle's oil injection control.

[0032] In this embodiment, the flow characteristics of the electromagnetic oil injection valve are highly linearly related to its opening time. Mechanical oil injectors, however, are greatly affected by rotational speed and have significant adjustment inertia, making precise fine-tuning at the single-cycle level impossible. This embodiment uses mapping transformation to directly physicalize the abstract wear compensation amount into specific valve opening microseconds, ensuring the accuracy of the oil injection quantity. The introduction of an electromagnet response lag compensation time constant is due to the physical delay between energizing the electromagnetic valve and the full opening of the valve core. Without compensation, the actual effective flow time will be less than the set time, resulting in insufficient oil injection. This compensation item eliminates the dynamic error of the actuator. Switching to the holding current immediately after a high-level trigger is chosen because a large number of ampere-turns is needed to overcome static friction and high voltage difference at the moment of opening, while maintaining opening only requires a smaller number of ampere-turns. This dual-current drive strategy ensures rapid action and avoids resistance changes caused by coil overheating, thus affecting the response speed. Applying a reverse demagnetizing voltage accelerates the disappearance of the magnetic field, and the reverse current generated by Lenz's law quickly eliminates residual magnetism, shortening the valve core reseating time. To prevent oil injection tailing caused by delayed closure and avoid lubricating oil leakage at unexpected times, the implementation of back pressure-based execution effect verification is introduced. This is because the proper functioning of the oil injection valve directly reflects the dynamic response of the pipeline pressure. If the valve core is stuck and not fully open, the pressure builds up slowly; if it is not tightly closed, the pressure cannot fall back to the reference value. By monitoring this physical characteristic, closed-loop monitoring from command issuance to action confirmation is achieved. This embodiment adopts electromagnetically driven pulse width modulation and dynamic phase locking technology, and integrates a self-diagnostic mechanism based on fluid dynamics characteristics. It can inject precisely measured lubricating oil at precise crankshaft rotation angles according to the calculated wear deviation value, ensuring that the quantity and timing control commands are restored without loss by the physical actuator. Especially under high wear risk conditions, the coordinated execution of advance phase and precise oil replenishment can ensure that the lubricating oil arrives accurately before the piston reaches the critical friction zone. At the same time, by monitoring the back pressure waveform in real time to identify valve body faults, the control strategy is prevented from failing due to actuator failure, eliminating the risk of partial oil cut-off.

[0033] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of the application as defined herein, and are to be considered as covering any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A method for oil injection control of a gas compressor cylinder, the method being applied to an oil injection system having a plurality of independent oil injection channels, each of the independent oil injection channels corresponding to an independent lubrication point on the cylinder, characterized in that, include: For each independent lubrication point, within one complete working cycle of the compressor, the time sequence of friction parameters at that independent lubrication point is continuously collected at a sampling rate higher than the piston motion frequency; The time sequence of the friction parameters is decomposed into waveforms to extract the feature parameters associated with the times when the piston ring passes through the top dead center and bottom dead center corresponding to the independent lubrication point. The characteristic parameters are input into a pre-built friction pair wear degradation model, the instantaneous wear rate of the current cycle of the independent lubrication point is output, and it is compared with the preset reference wear rate of the independent lubrication point to obtain the wear rate deviation value. Based on the wear rate deviation value and the current operating load of the gas compressor, determine the oil compensation amount and oil injection advance angle for this independent lubrication point; Based on the oil injection compensation amount and oil injection advance angle, the independent oil injection valve corresponding to the independent lubrication point is controlled to perform the oil injection action.

2. The coal gas compressor cylinder oil injection control method according to claim 1, characterized by, The friction parameters include instantaneous oil film thickness, instantaneous cylinder wall temperature, and instantaneous oil injection back pressure.

3. The coal gas compressor cylinder oil injection control method of claim 1, wherein, The waveform decomposition includes: Based on the crankshaft angle signal, the time-domain friction parameter time series is reconstructed into a crankshaft angle domain equal-angle interval series to eliminate phase distortion caused by speed fluctuations.

4. The coal gas compressor cylinder oil injection control method of claim 1, wherein, The characteristic parameters include the valley value of oil film thickness, the peak value of temperature, and the abrupt slope of the injection back pressure.

5. The method for controlling oil injection in the cylinder of a gas compressor according to claim 4, characterized in that, The extraction of feature parameters associated with the times when the piston ring corresponding to the independent lubrication point passes through top dead center and bottom dead center includes: Based on the crankshaft angle signal, the times when the piston rings pass through the top dead center and bottom dead center are determined respectively; The lowest value of the oil film thickness near the top dead center is extracted as the valley feature, and the highest value of the cylinder wall temperature near the bottom dead center is extracted as the peak feature. The maximum slope value at the instant the injection valve opens on the oil injection back pressure curve is extracted as the abrupt change slope feature.

6. The method for controlling oil injection in the cylinder of a gas compressor according to claim 1, characterized in that, The friction pair wear degradation model is constructed based on the Achad wear theory. It outputs the instantaneous wear rate through multi-dimensional coupling mapping of oil film thickness valley, cylinder wall temperature peak, and injection back pressure abrupt change slope.

7. The method for controlling oil injection in the cylinder of a gas compressor according to claim 6, characterized in that, The friction pair wear degradation model determines the boundary lubrication contact probability by the oil film thickness valley value, corrects the material hardness attenuation coefficient by the cylinder wall temperature peak value, and compensates for the wear increment caused by oil supply lag by the oil injection back pressure abrupt change slope.

8. The method for controlling oil injection in the cylinder of a gas compressor according to claim 1, characterized in that, The oil injection compensation amount is positively correlated with the wear rate deviation value, and an operating load correction coefficient is introduced to increase the compensation amount gain under high load conditions.

9. The method for controlling oil injection in the cylinder of a gas compressor according to claim 1, characterized in that, Methods for determining the oil injection advance angle include: When the wear rate deviation is greater than zero, the oil injection advance angle is advanced relative to the standard oil injection phase angle according to the magnitude of the deviation value. The advance angle is positively correlated with the deviation value.

10. The method for controlling oil injection in the cylinder of a gas compressor according to claim 1, characterized in that, Controlling the independent injection valve to perform the injection action includes: Using the crankshaft rotation angle as the trigger reference, the oil injection valve is activated at the target oil injection trigger angle; The valve opening pulse width is determined based on the oil injection compensation amount, and a driving method combining peak drive and holding current is adopted. After the oil injection is completed, the characteristics of the oil injection back pressure falling edge are collected to determine whether the valve core is stuck or not closed tightly.

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