A method for oil sample collection and analysis of a two-stroke engine

Abstract

This application provides a method for collecting and analyzing oil samples from a two-stroke engine, relating to the field of engine oil sample collection and analysis technology. The method involves establishing a flushing space within the engine cylinder while maintaining a closed exhaust port. Fuel is then injected in a predetermined amount. While keeping the exhaust port closed, the engine crankshaft is rotated reciprocally to create a dynamic flushing flow within the cylinder, flushing the inner surface and removing wear particles and carbon deposits, thus obtaining a mixed oil sample. This method overcomes the bottleneck of obtaining effective analytical samples from two-stroke engines due to fuel consumption during combustion, enabling effective monitoring of the wear condition of this type of engine. Ferrographic analysis based on the collected mixed oil sample allows for timely understanding of internal carbon deposits and wear conditions, enabling maintenance measures to be taken before failures occur. It achieves effective assessment of the internal condition of various models of two-stroke engines without complex modifications to the engine structure, effectively improving their operational reliability and service life.

Description

Technical Field

[0001] This application generally relates to the field of engine oil sample collection and analysis technology, and specifically to a method for oil sample collection and analysis of a two-stroke engine. Background Technology

[0002] A two-stroke engine is an internal combustion engine whose working cycle (intake, compression, power, and exhaust) is completed within two strokes of the piston (i.e., one revolution of the crankshaft).

[0003] In the field of engine oil sampling, current methods typically involve directly extracting fuel from the engine's fuel lines or the medium containing the fuel within the engine itself for analysis. However, for two-stroke engines, because all the fuel within the engine is consumed during combustion, it is impossible to obtain effective analyzable oil samples. Furthermore, during operation, carbon deposits gradually form inside two-stroke engines. When these deposits form in the intake manifold, they roughen the inner wall, affecting the formation and concentration of the combustible mixture. When carbon deposits form between the piston rings, they can cause piston ring sticking and cylinder wall scoring. When carbon deposits form on the piston crown or in the combustion chamber, they reduce the combustion chamber volume and increase the compression ratio. These problems make it crucial to regularly collect and analyze the oil from two-stroke engines to effectively reduce engine failure rates and extend their service life. However, in practical applications of two-stroke engines, there has been no precedent for obtaining effective analytical samples. Therefore, solving the problem of effectively collecting and preparing spectral samples from two-stroke engines has become a pressing technical challenge in this field. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide a method for oil sample collection and analysis of a two-stroke engine that can solve the above-mentioned technical problems.

[0005] This application provides a method for oil sample collection and analysis of a two-stroke engine, comprising the following steps:

[0006] A flushing space is established within the engine cylinder, and the exhaust port of the flushing space is kept closed.

[0007] Fuel is injected into the flushing space at a first predetermined amount;

[0008] While keeping the exhaust port closed, the engine crankshaft is rotated repeatedly for a preset number of cycles, causing the fuel to flow back and forth in the cylinder to flush the inner surface, thereby washing away the wear particles and carbon deposits attached thereto and mixing them into the fuel to form a mixed oil sample.

[0009] Collect the mixed oil sample;

[0010] Ferrographic analysis was performed on the mixed oil sample to determine the wear stage of the engine.

[0011] According to the technical solution provided in this application, before establishing a flushing space in the cylinder of the engine and maintaining the exhaust port of the flushing space in a closed state, the following steps are also included:

[0012] Determine the volume of a single cylinder in the engine;

[0013] Obtain a flushing parameter database, which includes at least: multiple sets of cylinder volume ranges and the fuel injection amount range and cycle number range corresponding to each set of cylinder volume ranges;

[0014] By traversing the flushing parameter database, when it is determined that the volume of a single cylinder is within any cylinder volume range, the first predetermined amount and the preset number of cycles corresponding to the reciprocating rotation of the engine crankshaft are determined within the corresponding range of fuel injection amount and the range of cycle number.

[0015] According to the technical solution provided in this application, the fuel injection range is generated based on the following rules:

[0016] Define the reference cylinder volume range and its corresponding reference fuel injection quantity range;

[0017] For each cylinder volume range following the reference cylinder volume range, the corresponding fuel injection range is formed by adding a first preset value range to the upper limit of the fuel injection range of the previous cylinder volume range.

[0018] According to the technical solution provided in this application, the range of the number of iterations is generated based on the following rules:

[0019] Define the reference cylinder volume range and its corresponding reference cycle number range;

[0020] For each cylinder volume range following the reference cylinder volume range, the corresponding cycle number range is formed by adding a second preset value range to the upper limit of the cycle number range of the previous cylinder volume range.

[0021] According to the technical solution provided in this application, ferrographic analysis is performed on the mixed oil sample to determine the wear stage of the engine, including the following steps:

[0022] Ferrographs were used to prepare spectra of the wear particles in the mixed oil sample.

[0023] The spectra were observed using a microscope and image analysis system to capture and analyze the morphological characteristics of the wear particles;

[0024] Based on the morphological characteristics of the wear particles, the wear stage of the engine is determined.

[0025] According to the technical solution provided in this application, the wear stages include the break-in period, the normal wear period, and the abnormal wear period.

[0026] According to the technical solution provided in this application, a flushing space is established within the cylinder of an engine, and the exhaust port of the flushing space is kept closed, comprising the following steps:

[0027] Remove the engine spark plugs to open the spark plug mounting holes;

[0028] Rotate the engine crankshaft to move the piston to a position that closes the exhaust port of the cylinder.

[0029] According to the technical solution provided in this application, injecting fuel into the flushing space in a first predetermined amount includes:

[0030] The first predetermined amount of fuel is injected into the flushing space through the spark plug mounting hole.

[0031] According to the technical solution provided in this application, collecting the mixed oil sample includes:

[0032] The mixed oil sample was collected through the spark plug mounting hole.

[0033] According to the technical solution provided in this application, after collecting the mixed oil sample, the following steps are also included:

[0034] Rotate the engine crankshaft to open the exhaust port and expel the residual oil mixture from the cylinder.

[0035] Reinstall the engine spark plug into the spark plug mounting hole and tighten it to the specified torque.

[0036] The beneficial effects of this application are as follows:

[0037] This application provides a method for collecting and analyzing oil samples from a two-stroke engine. First, a flushing space is established in the engine cylinder while keeping the exhaust port closed. Then, fuel is injected in a first predetermined amount. While keeping the exhaust port closed, the engine crankshaft is rotated repeatedly for a preset number of cycles to form a dynamic flushing flow in the cylinder. This flushes the inner surface and washes away wear particles and carbon deposits attached thereto, ultimately obtaining a representative mixed oil sample.

[0038] This method overcomes the technical bottleneck of obtaining effective analytical samples for two-stroke engines due to fuel consumption during combustion, enabling effective monitoring of the wear condition of this type of engine. Ferrographic analysis based on the collected mixed oil samples can accurately identify the wear stage of the engine, promptly grasp the internal carbon deposits and wear status, and thus take targeted maintenance measures before failure occurs. This application achieves effective assessment of the internal condition of various models of two-stroke engines without complex modifications to the engine structure, effectively improving their operational reliability and service life. Attached Figure Description

[0039] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0040] Figure 1 This is a flowchart of an oil sample collection and analysis method for a two-stroke engine provided in Embodiment 1 of this application;

[0041] Figure 2 This is a schematic diagram of a two-stroke engine extracting a mixed oil sample, as provided in Embodiment 1 of this application.

[0042] Figure 3 This is a schematic diagram of the alternating clockwise and counterclockwise rotation of the engine crankshaft provided in Embodiment 1 of this application;

[0043] Figure 4 This is a schematic diagram of the wear particle image before processing in the ferrography image intelligent analysis software system provided in Embodiment 1 of this application;

[0044] Figure 5 This is a schematic diagram of the wear particle image after processing by the ferrography image intelligent analysis software system provided in Embodiment 1 of this application.

[0045] In the diagram: 1. Two-stroke engine; 2. Engine crankshaft; 3. Injector; 4. Spark plug mounting hole. Detailed Implementation

[0046] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] Example 1

[0049] Please refer to Figure 1The flowchart of a method for collecting and analyzing oil samples from a two-stroke engine provided in this application includes the following steps:

[0050] S100: Establish a flushing space within the engine cylinder and maintain the exhaust port of the flushing space in a closed state.

[0051] Specifically, this application effectively seals the exhaust port of the two-stroke engine 1, creating a temporary enclosed area inside the cylinder capable of containing and circulating flushing fluid. This structure not only provides the necessary space for the reciprocating flow and flushing behavior of fuel within the cylinder but also effectively prevents fuel and the washed-off wear particles, carbon deposits, and other analytical targets from leaking from the exhaust port, thereby ensuring that the resulting mixed oil sample has sufficient representativeness and analytical value. This design specifically addresses the technical dilemma of obtaining effective oil samples from the two-stroke engine 1 through conventional means due to fuel consumption, laying the necessary structural foundation for reliable oil sample collection and accurate ferrographic analysis.

[0052] Further, step S100 includes the following steps:

[0053] S101: Remove the engine spark plugs to open the spark plug mounting holes;

[0054] S102: Rotate the engine crankshaft to move the piston to the position of the exhaust port that closes the cylinder.

[0055] Specifically, the operator needs to remove the engine spark plugs, leaving the spark plug mounting hole 4 open. This hole will serve as the main channel for subsequent flushing fluid injection and oil sample collection. Then, by rotating the engine crankshaft 2, the position of the piston within the cylinder is precisely controlled, moving it to a position that completely covers and seals the cylinder exhaust port. This crucial step ensures that a relatively closed flushing space is formed inside the cylinder during subsequent flushing, effectively preventing flushing fluid from escaping from the exhaust port, thus guaranteeing the flushing effect and allowing the flushed abrasive particles and carbon deposits to be fully retained in the flushing fluid.

[0056] Specifically, in this embodiment, the fuel (i.e., oil) randomly supplied with the engine is selected as the flushing fluid to systematically flush the inside of the cylinder; this fuel can be directly taken from the engine's daily fuel supply system, and its composition is completely consistent with the actual working fluid when the engine is running. In particular, for the two-stroke engine 1 that adopts a mixed lubrication method, this fuel already contains an appropriate amount of lubricating oil components in a standard proportion.

[0057] The technical advantages of this flushing fluid selection are as follows: First, it ensures complete compatibility between the flushing fluid and the engine material and residual oil film, avoiding material corrosion or chemical reactions that may be caused by external solvents. Second, the fuel itself has excellent dissolving and suspending capabilities for deposits such as carbon deposits and sludge formed during engine operation, effectively improving the flushing effect. Third, the lubricating oil components in the fuel can exert their lubricating properties, providing necessary protection for moving parts during the flushing process. By using the engine's original fuel, the safety and effectiveness of the flushing process are guaranteed, and the sampling environment is highly consistent with the actual operating environment, providing an important guarantee for obtaining oil samples that truly reflect the engine's wear condition.

[0058] Furthermore, the following steps are included before step S100:

[0059] Determine the volume of a single cylinder in the engine;

[0060] Obtain a flushing parameter database, which includes at least: multiple sets of cylinder volume ranges and the fuel injection quantity range and cycle number range corresponding to each set of cylinder volume ranges;

[0061] By traversing the flushing parameter database, when it is determined that the volume of a single cylinder is within any cylinder volume range, the first predetermined amount and the preset number of cycles corresponding to the reciprocating rotation of the engine crankshaft are determined within the corresponding fuel injection amount range and cycle number range.

[0062] Specifically, before formally performing the flushing space construction and oil sample collection operations, this application also includes a parameter preset process based on the specific model and operating conditions of the two-stroke engine 1. This process is implemented through a computing device (such as a dedicated diagnostic instrument, industrial computer, or mobile terminal) with a built-in control system. The system first requires the operator to input or automatically obtain the volume of a single cylinder of the target engine as the core parameter input; based on this, the control system will call the flushing parameter database, which includes at least: multiple sets of cylinder volume ranges and the range of fuel injection quantity and crankshaft reciprocating rotation cycles corresponding to each set of cylinder volume ranges.

[0063] In practice, by traversing the cylinder volume ranges in the database, the control system can automatically identify the range to which the current engine's individual cylinder volume belongs, and accordingly retrieve the corresponding fuel injection quantity range and cycle count range. Within this fuel injection quantity range and cycle count range, the operator determines the specific fuel injection quantity required for this flushing operation (this specific fuel injection quantity is the first predetermined quantity selected for this operation) and the preset number of crankshaft reciprocating rotations. This parameter preset mechanism ensures that engines of different specifications can obtain the most suitable flushing intensity and duration for their structural characteristics, guaranteeing the effectiveness of the flushing while avoiding resource waste or insufficient cleaning caused by improper parameters.

[0064] Furthermore, the fuel injection range is generated based on the following rules:

[0065] Define the reference cylinder volume range and its corresponding reference fuel injection quantity range;

[0066] For each cylinder volume range following the baseline cylinder volume range, the corresponding fuel injection range is formed by adding a first preset value range to the upper limit of the fuel injection range of the previous cylinder volume range.

[0067] Specifically, the generation of the fuel injection range follows a rigorous, step-by-step progression rule. Firstly, the cylinder volume range of 0-200ml is defined as the baseline volume range, with a corresponding baseline fuel injection range of 20ml-30ml. For larger volume ranges exceeding this baseline range, the system divides subsequent ranges into fixed intervals of 200ml, i.e., sequentially setting continuous cylinder volume ranges such as 200ml-400ml, 400ml-600ml, etc. The fuel injection range for each subsequent cylinder volume range is formed by adding a first preset value range to the upper limit of the fuel injection range of the previous cylinder volume range; in this embodiment, the first preset value range is 20ml-30ml.

[0068] Taking practical applications as an example: when the cylinder volume range is 200ml-400ml, the fuel injection range is the upper limit of the baseline fuel injection range of 30ml plus 20ml-30ml, forming a fuel injection range of 50ml-60ml; when the volume is further increased to the range of 400ml-600ml, it is further increased by 20ml-30ml on the basis of the upper limit of the previous fuel injection range of 60ml, forming a fuel injection range of 80ml-90ml.

[0069] This parameter generation mechanism ensures a scientific match between the flushing fluid volume and the engine capacity, guaranteeing both sufficient flushing fluid and avoiding sample dilution caused by excessive flushing. Through this standardized parameter progression rule, precise control of the flushing intensity for engines of different specifications is achieved, providing reliable parameter assurance for obtaining representative oil samples.

[0070] Furthermore, the range of loop counts is generated based on the following rules:

[0071] Define the reference cylinder volume range and its corresponding reference cycle number range;

[0072] For each cylinder volume range after the baseline cylinder volume range, the corresponding cycle number range is formed by adding a second preset value range to the upper limit of the cycle number range of the previous cylinder volume range.

[0073] Specifically, the generation of the cycle count range also follows a step-by-step progression rule coordinated with the fuel injection amount. Specifically, the baseline cycle count range corresponding to the baseline cylinder volume range of 0-200ml is first set to 60-80 times. For larger volume ranges exceeding this baseline range, the system divides subsequent ranges into fixed intervals of 200ml, i.e., sequentially setting consecutive volume ranges such as 200ml-400ml, 400ml-600ml, etc. The cycle count range for each subsequent cylinder volume range is formed by adding a second preset value range to the upper limit of the cycle count range of the previous cylinder volume range; in this embodiment, the second preset value range is 20-40 times.

[0074] Taking practical applications as an example: when the cylinder volume range is 200ml-400ml, the number of cycles is the upper limit of the baseline number of cycles range of 80 times, increased by 20-40 times, forming a number of cycles range of 80-120 times; when the volume is further increased to the range of 400ml-600ml, the number of cycles is increased by 20-40 times on the basis of the upper limit of the previous number of cycles range of 120 times, forming a number of cycles range of 140-160 times.

[0075] This design ensures a system match between flushing intensity and engine volume: smaller engines can achieve effective flushing with moderate circulation, while larger engines require increased circulation to ensure the flushing fluid fully covers the entire cylinder surface. This parameter generation mechanism, together with the fuel injection quantity rules, constitutes a complete flushing parameter system, providing crucial technical support for obtaining representative fuel samples.

[0076] S200: Inject fuel into the flushing space at a first predetermined amount;

[0077] Specifically, when a single cylinder volume is determined to be within a certain range, the operator does not simply use a fixed value. Instead, based on the engine's actual operating condition and maintenance needs, they flexibly select an appropriate specific value as the first predetermined amount within the corresponding fuel injection range. For example, for engines with a cylinder volume in the 200-400ml range, although the corresponding fuel injection range is 40-60ml, in actual operation, the appropriate first predetermined amount can be selected within this range based on the engine's usage time, the severity of carbon buildup, and other actual conditions: for engines with severe carbon buildup or those that have not been maintained for a long time, 60ml, close to the upper limit, can be selected as the first predetermined amount to ensure thorough flushing; while for engines in good condition or those requiring only routine monitoring, 40ml, close to the lower limit, can be selected as the first predetermined amount.

[0078] Further, step S200 includes: injecting the first predetermined amount of fuel into the flushing space through the spark plug mounting hole.

[0079] Specifically, fuel is injected into the established flushing space through the spark plug mounting hole 4 created after the engine spark plug is removed. This design makes full use of the existing engine structure, without requiring additional holes or structural modifications to the engine body. During operation, a syringe 3 is used to inject a first predetermined amount of fuel into the cylinder at a controlled rate.

[0080] S300: While keeping the exhaust port closed, the engine crankshaft is rotated back and forth according to a preset number of cycles, so that the fuel flows back and forth in the cylinder to flush the inner surface, thereby washing off the wear particles and carbon deposits attached to it and mixing them into the fuel to form a mixed oil sample.

[0081] Specifically, the rotation of the engine crankshaft 2 is performed in a small-amplitude alternating clockwise and counterclockwise manner (e.g., Figure 3 (As indicated by the middle arrow), ensuring the piston always covers the exhaust port during movement, maintaining the sealing of the flushing space. This dynamic flushing mechanism fully utilizes the fluid properties of the fuel, effectively washing away wear particles, carbon deposits, and other sediments adhering to the inside of the cylinder through repeated flushing action. The washed-off particles are then suspended in the fuel, forming a homogeneous mixture that accurately reflects the wear condition inside the engine.

[0082] During this process, the thoroughness of the flushing is ensured by a preset number of cycles; the selection of the preset number of cycles reflects the scientific nature and flexibility of this method in practical applications. When the engine cylinder volume is determined to be within a certain cylinder volume range, the operator needs to select an appropriate specific value within the corresponding number of cycles based on the actual operating conditions of the engine.

[0083] Taking engines with a cylinder volume of 200-400ml as an example, although the standard cycle count range is 80-120 times, precise selection requires comprehensive consideration of various factors in actual operation: for engines with long operating time and significant carbon buildup, or those found to have a large number of early wear particles during regular maintenance, a cycle count close to the upper limit of the range (e.g., 100-120 times) should be selected to ensure sufficient flushing effect; while for engines in good operating condition and with normal maintenance records, a cycle count close to the lower limit of the range (e.g., 80-100 times) can be used. This flexible parameter selection mechanism fully considers individual engine differences and actual wear conditions, ensuring basic flushing effect while avoiding resource waste caused by excessive operation. By combining theoretical parameter ranges with actual operating conditions, this method can adapt to the testing needs of different usage scenarios, ensuring the representativeness of oil samples while also demonstrating practicality and economy in engineering applications.

[0084] S400: Collect mixed oil samples;

[0085] Further, step S400 includes: collecting the mixed oil sample via the spark plug mounting hole.

[0086] Specifically, such as Figure 2 As shown, the mixed oil sample is extracted through the spark plug mounting hole 4. This design maintains consistency in the operating channel and eliminates the need for additional openings on the engine block. In practice, the operator uses a syringe 3 to slowly extract the mixed oil sample by inserting it into the cylinder through the spark plug mounting hole 4.

[0087] To ensure the representativeness of the collected oil samples, the following points should be noted during the extraction process: First, the samples should be collected within a short period of time after rinsing to avoid precipitation of suspended particles; second, the extraction should be carried out at a uniform and slow speed to ensure that the oil sample contains wear particles eluted from different parts of the cylinder; finally, the sample volume should be sufficient to meet the requirements of ferrography analysis.

[0088] Furthermore, the following steps are included after step S300:

[0089] S310: Rotate the engine crankshaft to open the exhaust port and expel the residual oil mixture from the cylinder.

[0090] S320: Reinstall the engine spark plug into the spark plug mounting hole and tighten it to the specified torque.

[0091] Specifically, after collecting the mixed oil sample, this application also includes key post-processing steps to ensure the integrity of the engine and its subsequent normal use.

[0092] First, slowly rotate the engine crankshaft 2 to move the piston to a position where it no longer covers the exhaust port. At this point, the exhaust port is fully open, and the cylinder interior is connected to the atmosphere. This operation allows any small amount of mixed oil that may remain at the bottom of the cylinder, in the piston ring gaps, or in dead corners of the cylinder cavity to be naturally expelled by gravity. If necessary, compressed air or a special liquid suction device can be used to assist in cleaning through the spark plug mounting hole 4 to ensure that no flushing fluid remains inside the cylinder.

[0093] Next, the original engine spark plugs were cleaned and reinstalled into spark plug mounting holes 4, and tightened to the engine's specified standard torque value using a torque wrench. This step is crucial, as it not only restores the engine's structural integrity but also ensures the combustion chamber's sealing performance, guaranteeing subsequent engine starting and normal operation.

[0094] S500: Perform ferrographic analysis on mixed oil samples to determine the wear stage of the engine.

[0095] Further, step S500 includes the following steps:

[0096] S501: Using a ferrometer to prepare spectra of wear particles in a mixed oil sample;

[0097] S502: Observe the spectrum using a microscope and image analysis system to capture and analyze the morphological characteristics of wear particles;

[0098] S503: Determine the wear stage of the engine based on the morphological characteristics of wear particles.

[0099] Specifically, in ferrography, a barometric analysis method is used to systematically analyze the mixed oil sample. The specific implementation process is as follows:

[0100] Add the special cleaning solution to the analytical ferrography instrument as required, complete the power connection, and strictly check the airtightness of the system to ensure that the instrument is in normal working condition.

[0101] The collected mixed oil sample was injected into the oil delivery tube of the ferrography instrument, and then a shaker was used to homogenize the oil sample, so that the wear particles suspended in the oil were fully dispersed and kept evenly distributed.

[0102] During the spectral preparation process, the "normal speed" and "transport" modes were selected for preparing the abrasive spectral slides. After the slides were formed, a standardized cleaning procedure was followed to remove residual oil, and the slides were then allowed to air dry in a dust-free environment to obtain complete spectral slides suitable for observation.

[0103] The ferrography image intelligent analysis software system was launched, and connected to a microscope, industrial digital camera, and interface converter to establish a complete image acquisition and analysis platform. Utilizing the software's "real-time transmission" and "capture" functions, the system acquired complete morphological information of the wear particles; through the system's built-in "judgment" function, the particle characteristics were intelligently identified and analyzed to determine the wear stage of the engine. Figures 4-5 The diagram shows a comparison of the system's processing of wear particle images before and after processing, visually demonstrating the system's processing performance in wear particle identification and classification.

[0104] Furthermore, the wear stages include the break-in period, the normal wear period, and the abnormal wear period.

[0105] Specifically, the judgment criteria established based on a large amount of experimental data are as follows: when the wear particles are in the form of running-in abrasive particles, small-sized cutting abrasive particles, and spherical abrasive particles, the engine is judged to be in the running-in period; when the wear particles are in the form of normal wear particles mainly composed of cast iron, carbon steel, copper alloy, aluminum alloy, and lead / tin alloy powder, the engine is judged to be in the normal wear period; and when the wear particles are in the form of abnormal particles such as severely sliding abrasive particles, fatigue abrasive particles, large-sized cutting abrasive particles, or friction polymers, the engine is judged to have entered the abnormal wear period.

[0106] In a practical application case, the data obtained from the ferrography analysis of the collected mixed oil samples are shown in Table 1.

[0107] Table 1. Data obtained from ferrographic analysis of mixed oil samples.

[0108]

[0109] The analysis results show that severe abrasive wear accounted for 82%, abrasive wear accounted for 18%, and other wear forms accounted for 0%, which is consistent with the typical characteristics of an abnormal wear period. This specific case verifies that the method can effectively identify abnormal wear conditions in engines, providing an accurate scientific basis for predictive maintenance and avoiding potential serious failures.

[0110] Working Principle: This application establishes a flushing space within the engine cylinder while maintaining a closed exhaust port. Fuel is then injected in a predetermined amount. While keeping the exhaust port closed, the engine crankshaft 2 is rotated repeatedly for a preset number of cycles, creating a dynamic flushing flow within the cylinder. This flushes the inner surface and removes wear particles and carbon deposits, ultimately obtaining a representative mixed oil sample. This method overcomes the technical bottleneck of obtaining effective analytical samples from two-stroke engines 1 due to fuel consumption during combustion, enabling effective monitoring of the wear state of this type of engine. Ferrographic analysis based on the collected mixed oil sample accurately identifies the engine's wear stage, allowing for timely assessment of internal carbon deposits and wear conditions, thus enabling targeted maintenance measures to be taken before failure occurs. This application achieves effective evaluation of the internal condition of various models of two-stroke engines 1 without complex modifications to the engine structure, effectively improving their operational reliability and service life.

[0111] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A method for collecting and analyzing oil samples from a two-stroke engine, characterized in that, Includes the following steps: A flushing space is established within the engine cylinder, and the exhaust port of the flushing space is kept closed. Fuel is injected into the flushing space at a first predetermined amount; While keeping the exhaust port closed, the engine crankshaft is rotated repeatedly for a preset number of cycles, causing the fuel to flow back and forth in the cylinder to flush the inner surface, thereby washing away the wear particles and carbon deposits attached thereto and mixing them into the fuel to form a mixed oil sample. Collect the mixed oil sample; Ferrographic analysis was performed on the mixed oil sample to determine the wear stage of the engine.

2. The method for oil sample collection and analysis of a two-stroke engine according to claim 1, characterized in that, Before establishing a flushing space within the engine cylinders and maintaining the exhaust port of the flushing space in a closed state, the following steps are also included: Determine the volume of a single cylinder in the engine; Obtain a flushing parameter database, which includes at least: multiple sets of cylinder volume ranges and the fuel injection amount range and cycle number range corresponding to each set of cylinder volume ranges; By traversing the flushing parameter database, when it is determined that the volume of a single cylinder is within any cylinder volume range, the first predetermined amount and the preset number of cycles corresponding to the reciprocating rotation of the engine crankshaft are determined within the corresponding range of fuel injection amount and the range of cycle number.

3. The method for oil sample collection and analysis of a two-stroke engine according to claim 2, characterized in that, The fuel injection range is generated based on the following rules: Define the reference cylinder volume range and its corresponding reference fuel injection quantity range; For each cylinder volume range following the reference cylinder volume range, the corresponding fuel injection range is formed by adding a first preset value range to the upper limit of the fuel injection range of the previous cylinder volume range.

4. The method for oil sample collection and analysis of a two-stroke engine according to claim 2, characterized in that, The range of the number of iterations is generated based on the following rules: Define the reference cylinder volume range and its corresponding reference cycle number range; For each cylinder volume range following the reference cylinder volume range, the corresponding cycle number range is formed by adding a second preset value range to the upper limit of the cycle number range of the previous cylinder volume range.

5. The method for oil sample collection and analysis of a two-stroke engine according to claim 1, characterized in that, Ferrographic analysis of the mixed oil sample to determine the wear stage of the engine includes the following steps: Ferrographs were used to prepare spectra of the wear particles in the mixed oil sample. The spectra were observed using a microscope and image analysis system to capture and analyze the morphological characteristics of the wear particles; Based on the morphological characteristics of the wear particles, the wear stage of the engine is determined.

6. The method for oil sample collection and analysis of a two-stroke engine according to claim 5, characterized in that, The wear stages include the break-in period, the normal wear period, and the abnormal wear period.

7. The method for oil sample collection and analysis of a two-stroke engine according to claim 1, characterized in that, Establishing a flushing space within the engine cylinder and maintaining the exhaust port of the flushing space in a closed state includes the following steps: Remove the engine spark plugs to open the spark plug mounting holes; Rotate the engine crankshaft to move the piston to a position that closes the exhaust port of the cylinder.

8. The method for oil sample collection and analysis of a two-stroke engine according to claim 7, characterized in that, Injecting fuel into the flushing space in a first predetermined amount includes: The first predetermined amount of fuel is injected into the flushing space through the spark plug mounting hole.

9. The method for oil sample collection and analysis of a two-stroke engine according to claim 7, characterized in that, Collecting the mixed oil sample includes: The mixed oil sample was collected through the spark plug mounting hole.

10. The method for oil sample collection and analysis of a two-stroke engine according to claim 7, characterized in that, After collecting the mixed oil sample, the following steps are also included: Rotate the engine crankshaft to open the exhaust port and expel the residual oil mixture from the cylinder. Reinstall the engine spark plug into the spark plug mounting hole and tighten it to the specified torque.

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