Compensation and determination method of research octane number under low pressure

Abstract

The application discloses a compensation method for researching octane number under low air pressure, and the researched octane number R of a sample after compensation is the researched octane number R1 plus the researched octane number compensation value of the sample, and the formula is R=R1+AR; the researched octane number compensation value AR of the sample is -0.08*P+7.25, wherein P is the atmospheric pressure during the test, and the unit is kPa. The application also discloses a determination method for researched octane number under low air pressure, wherein the compensation method is used for compensating the researched octane number in the two steps of calibrating an engine with toluene standard fuel and determining a gasoline sample. The application is an effective supplement to the current determination technology of the researched octane number, and improves the accuracy of the determination result of the researched octane number of vehicle gasoline under low air pressure. The application can systematically reflect the accurate compensation of the determination result of the researched octane number of vehicle gasoline under low air pressure, improve the accuracy of the determination result of the researched octane number of vehicle gasoline in a low air pressure area, and provide a basis for the quality control of vehicle gasoline in the low air pressure area.

Description

Technical Field

[0001] This invention relates to the field of gasoline anti-knock performance testing technology, specifically to a method for compensating and determining the octane number of the research method under low pressure. Background Technology

[0002] Research octane (ROC) is a measure of the ability of gasoline in spark-ignition engines to burn without knocking, also known as anti-knock performance. Gasoline with poor anti-knock performance, when the air-fuel mixture is compressed and ignited, generates a large amount of highly unstable peroxides, forming multiple combustion centers and resulting in violent, explosive combustion. This combustion impacts the piston head and cylinder, producing a crisp metallic knocking sound, commonly known as knocking combustion. Knocking combustion causes a sharp increase in engine cylinder temperature and pressure, overheating the cylinder head, burning valves, pistons, and piston rings, shortening engine life. It also causes the engine to emit black smoke, reduce power, increase fuel consumption, and lower its performance and fuel economy. Therefore, the ROC of automotive gasoline is crucial for its use. Engines with different compression ratios require gasoline with a matching ROC to ensure normal engine operation.

[0003] GB / T 5487-2015 "Research Method for Determination of Octane Number of Gasoline" and ASTM D2699 "Standard Test Method for Research Octane Number of Spark-Ignition Engine Fuel" specify the following for determining the research octane number (ROC) of automotive gasoline: A standard test engine is used under specified standard operating conditions. A dedicated electronic knock instrument is used to compare the knock characteristics of the sample automotive gasoline with a standard fuel mixture. Standard knock intensity is generated by adjusting the engine's compression ratio and air-fuel ratio. The ROC corresponding to the compression ratio is then found in the standard knock intensity table; this is the ROC of the sample automotive gasoline. Currently, the standard test engine used for determining the ROC of automotive gasoline is manufactured by Waukesha.

[0004] Factors such as fuel properties and engine operating conditions can affect the determination of the research octane number (RON) of automotive gasoline in standard test engines. From the perspective of spark-ignition engine combustion theory, when the excess air coefficient (the ratio of actual air supply to theoretical air requirement during combustion) is in the range of 0.8-0.9, the fuel is most prone to knocking combustion; when the excess air coefficient is in the range of 1.05-1.15, the fuel is less prone to knocking combustion, and the engine power is at its maximum. Therefore, under low-pressure conditions with low oxygen content, incomplete combustion of automotive gasoline is more likely to cause engine knocking.

[0005] In the field of testing technology for the anti-knock performance of automotive gasoline, the existing research method for determining the octane number of automotive gasoline has the following main problems:

[0006] (1) At low atmospheric pressure, especially when the atmospheric pressure is between 77.0 and 88.0 kPa, the results of the determination of the research octane number of automotive gasoline are generally lower than the true value of the research octane number of automotive gasoline. Moreover, the lower the atmospheric pressure, the greater the deviation between the two.

[0007] (2) Currently, regarding the determination of the research octane number under the above atmospheric pressure, various regions rely solely on experience to make corrections and compensations, and there is no systematic and comprehensive method for accurately determining the research octane number of automotive gasoline under low atmospheric pressure. Summary of the Invention

[0008] This invention addresses the problems in the prior art by disclosing a method for compensating and determining the research octane number under low pressure. This invention can be used for determining the research octane number of gasoline under low pressure, especially when the atmospheric pressure is 77.0 to 88.0 kPa.

[0009] By utilizing the linear relationship between oxygen content and atmospheric pressure at low pressure, this study aims to establish the relationship between research octane number (RON) and atmospheric pressure. A compensation formula for RON determination under low pressure conditions (especially 77.0–88.0 kPa) is developed, providing a method for determining the RON of gasoline under low pressure. This eliminates the problem of underestimating the RON of automotive gasoline under low pressure, ensuring that the test results accurately reflect the anti-knock performance of automotive gasoline and improving the accuracy of RON determination results. This is a technical problem that needs to be solved in this field.

[0010] This invention is achieved through the following technical solution:

[0011] This invention provides a method for compensating the research octane number (ROC) under low atmospheric pressure. The R of the compensated R of the sample is the R1 of the ROC plus the ROC compensation value of the sample, and the formula is: R = R1 + ΔR; the ROC compensation value of the sample is ΔR = -0.08 × P + 7.25, where P is the atmospheric pressure during the test, and its unit is kPa.

[0012] As a further step, the research octane number R1 is determined according to the method in standard GB / T 5487-2015.

[0013] As a further option, the atmospheric pressure during the test is 77.0–88.0 kPa.

[0014] The above-described design of the present invention compensates for the gasoline research octane number measured according to the method in standard GB / T 5487-2015 when the atmospheric pressure is low, especially when the atmospheric pressure is 77.0 to 88.0 kPa, thereby making the measured gasoline research octane number more accurate.

[0015] The present invention also provides a method for determining the research octane number under low pressure, comprising the following steps: (i) inspecting the engine; (ii) determining the standard knock intensity; (iii) calibrating the engine with toluene standard fuel; and (iv) measuring a gasoline sample.

[0016] In this case, step (ii) can be executed first and then step (iii), or step (iii) can be executed first and then step (ii);

[0017] In steps (iii) and (iv), the compensation method described above is used to compensate for the research octane number.

[0018] As a further embodiment, the method for determining the octane number of a gasoline sample using the aforementioned octane number compensation method includes the following specific steps:

[0019] (1) Inspect the engine

[0020] The engine was checked to ensure it met standard operating conditions, consistent with operating conditions using a specific fuel at standard knock intensity. The specific fuel was confirmed according to the description in standard GB / T 5487-2015.

[0021] (2) Determine the standard knock intensity

[0022] Select positive standard fuel with an octane rating within the range required by standard GB / T 5487-2015 to supply fuel to the engine. Change the compression ratio to the value required by the operation table. Under the maximum knock fuel-air ratio, adjust the knock meter to make the knock meter reading 50±2.

[0023] (3) Engine calibrated with toluene standard fuel

[0024] Engine suitability tests were conducted using toluene standard fuel whose octane rating was within the range required by standard GB / T 5487-2015 for the sample gasoline. The engine was supplied with toluene standard fuel, and the compression ratio was adjusted to a knock gauge reading of 50. At the maximum knock fuel-air ratio, without changing the positive knock intensity reading on the knock gauge, the compression ratio was adjusted to a knock gauge reading of 50±2. The research octane rating of the toluene standard fuel was obtained from the standard knock intensity operation table. The compensation for the toluene standard fuel test result under the test atmospheric pressure was calculated using the research octane rating compensation formulas ΔR=-0.08×P+7.25 and R=R1+ΔR. The compensated research octane rating of the toluene standard fuel was compared with the standard value to check the engine test deviation and determine the engine's suitability performance.

[0025] If the deviation is within ±0.3, the engine is suitable for determining the research octane number of automotive gasoline samples within a selected octane range. The selected octane range is the range of octane numbers of the automotive gasoline samples to be tested, selected according to standard GB / T 5487-2015.

[0026] If the deviation exceeds ±0.3 by 0.1 units, the intake air temperature may be adjusted to achieve a specific toluene standard fuel octane number.

[0027] If the deviation exceeds ±0.3, the adjusted intake temperature at the current atmospheric pressure and standard intake temperature should not exceed ±40℉. If, after temperature adjustment, the toluene standard fuel octane number is within ±0.1 units of the standard value, the engine is suitable for testing within the octane number range of the sample vehicle gasoline. If, after temperature adjustment, the toluene standard fuel octane number exceeds ±0.1 units of the standard value, the engine is not suitable for testing within the octane number range of the sample gasoline. Testing can only proceed after the cause has been identified and eliminated to meet the deviation requirements.

[0028] In accordance with the conventions of those skilled in the art, the aforementioned deviation exceeding ±0.3 by 0.1 units refers to a deviation exceeding ±0.3 + 0.1; the octane number within ±0.1 units of the standard value refers to the standard octane number within ±0.1 units.

[0029] (4) Determination of automotive gasoline samples

[0030] A gasoline sample was selected and supplied with fuel to the engine. The compression ratio was changed until the knock gauge reading was 50. Under the maximum knock fuel-air ratio, the compression ratio was readjusted until the knock gauge reading was 50 ± 2. The counter reading was recorded, and the corresponding research octane number (RON) for the compression ratio was found in the standard knock intensity operation table. The RON compensation formula ΔR = -0.08 × P + 7.25 and R = R1 + ΔR was used to calculate the RON compensation for the gasoline sample under the test atmospheric pressure conditions. The RON of the gasoline sample after compensation is the final RON determined for the gasoline sample.

[0031] (5) Engine stopped

[0032] Close the fuel valve, drain the fuel from the fuel cup, turn off the heating and ignition switches, run the engine for 1 minute, turn off the engine switch, turn off the cooling and intake devices, rotate the engine 4-5 times to stop the flywheel at the top dead center of the compression stroke, and disconnect the main power supply.

[0033] The features and beneficial effects of this invention are as follows:

[0034] (1) By utilizing the linear relationship between oxygen content and atmospheric pressure under low pressure (especially under conditions above 77.0 kPa), the quantitative relationship between octane number compensation value and atmospheric pressure is determined, providing a basis for octane number determination under low pressure.

[0035] (2) At low atmospheric pressure, especially under the conditions of 77.0 to 88.0 kPa, by compensating for the test engine's gasoline octane number determination results, the deficiency of the gasoline octane number determination results being too low under this atmospheric pressure can be made up, so that the determination results can accurately reflect the anti-knock performance of gasoline.

[0036] (3) This invention solves the problem of accuracy of gasoline research octane number determination results under low atmospheric pressure, especially under conditions of 77.0 to 88.0 kPa, improves the existing method for determining gasoline research octane number in high-altitude areas, and improves the accuracy of gasoline research octane number determination results under atmospheric pressure in this range. Attached Figure Description

[0037] Figure 1 The results of the octane number determination under different atmospheric pressures in the embodiments of the present invention are shown. Detailed Implementation

[0038] To facilitate understanding of the method for compensating and determining octane number under low pressure according to the present invention, a more comprehensive description of the method for compensating and determining octane number under low pressure according to the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0039] It should be noted that the technical terms involved in this invention, such as research octane number, compression ratio, knock gauge reading, maximum knock fuel-air ratio, counter (including upper and lower counters, generally referring to the lower counter), toluene standard fuel, and specific fuel (toluene standard fuel or positive standard fuel), are all general technical terms in the standard GB / T 5487-2015.

[0040] This invention relates to a method for compensating for the research octane number (ROC) under low pressure. By fitting the ROC measurement data under low pressure conditions, especially 77.0–88.0 kPa, a relationship between atmospheric pressure P and the ROC compensation value ΔR is proposed. This provides an effective supplement to current ROC measurement methods and improves the accuracy of ROC measurements for automotive gasoline. The ROC compensation value ΔR for the sample is -0.08 × P + 7.25, where P is the atmospheric pressure during the test (in kPa), and ΔR is the ROC compensation value. The ROC of the automotive gasoline after compensation, i.e., the final ROC measurement value, is the R of the gasoline measured according to the method in standard GB / T 5487-2015 plus the ROC compensation value ΔR of the sample, as follows: R = R1 + ΔR.

[0041] This invention also relates to a method for determining the octane number using a research method under low pressure, the specific steps of which are as follows:

[0042] 1. Check the engine

[0043] Check that the engine meets standard operating conditions, consistent with operating conditions using specific fuel at standard knock intensity.

[0044] 2. Determine the standard knock intensity

[0045] Select positive-standard fuel with an octane rating within the range required by standard GB / T 5487-2015 for the test vehicle and supply it to the engine. Change the compression ratio to the value required by the operation table. Under the maximum knock fuel-air ratio, adjust the knock meter to make the knock meter reading 50±2.

[0046] 3. Engine calibrated with toluene standard fuel

[0047] Engine suitability tests were conducted using toluene standard fuel with an octane rating within the range required by standard GB / T 5487-2015 for gasoline used in the test vehicle. The engine was supplied with toluene standard fuel, and the compression ratio was adjusted to a knock gauge reading of 50. At the maximum knock fuel-air ratio, without changing the positive knock intensity reading on the knock gauge, the compression ratio was adjusted to a knock gauge reading of 50±2. The research octane rating of the toluene standard fuel was obtained from the standard knock intensity operation table. The compensation formula for the research octane rating under low pressure, ΔR = -0.08 × P + 7.25 and R = R1 + ΔR, was used to calculate the compensation for the toluene standard fuel test results under the test atmospheric pressure. The compensated research octane rating of the toluene standard fuel was compared with the standard value to check the engine test deviation and determine the engine's suitability performance.

[0048] If the deviation is within ±0.3, the engine is suitable for determining the research octane number of gasoline samples for vehicles within the selected octane number range.

[0049] If the deviation exceeds ±0.3 by 0.1 units, the intake air temperature may be adjusted to achieve a specific toluene standard fuel octane number.

[0050] If the deviation exceeds ±0.3, the adjusted intake temperature at the current atmospheric pressure and standard intake temperature should not exceed ±40℉. If, after temperature adjustment, the toluene standard fuel octane number is within ±0.1 units of the standard value, the engine is suitable for testing within the octane number range of the sample vehicle's gasoline. If, after temperature adjustment, the toluene standard fuel octane number exceeds ±0.1 units of the standard value, the engine is not suitable for testing within the octane number range of the sample vehicle's gasoline. Testing can only proceed after the cause has been identified and eliminated to meet the deviation requirements.

[0051] 4. Testing of automotive gasoline samples

[0052] A gasoline sample was selected and supplied to the engine. The compression ratio was changed to make the knock gauge reading 50. Under the maximum knock fuel-air ratio, the compression ratio was readjusted to make the knock gauge reading 50±2. The counter reading was recorded, and the corresponding research octane number (RON) for the compression ratio was found in the standard knock intensity operation table. The RON compensation for the gasoline sample under test atmospheric pressure was calculated using the low-pressure RON compensation formulas ΔR=-0.08×P+7.25 and R=R1+ΔR. The RON compensation for the gasoline sample under test atmospheric pressure was then calculated. The RON compensation of the gasoline sample is the final RON determined for the gasoline sample.

[0053] 5. Engine stopped

[0054] Close the fuel valve, drain the fuel from the fuel cup, turn off the heating and ignition switches, run the engine for 1 minute, turn off the engine switch, turn off the cooling and intake devices, rotate the engine 4-5 times to stop the flywheel at the top dead center of the compression stroke, and disconnect the main power supply.

[0055] Example 1:

[0056] To more clearly illustrate the compensation and determination method for octane number under low pressure in this invention, the method for determining the octane number of a 92-octane gasoline sample at an atmospheric pressure of 81.0 kPa is described in more detail below:

[0057] 1. Check the engine

[0058] 1) Check that the counter value is below 500.

[0059] 2) Lubricate all oiling points, manually rotate the flywheel clockwise 4-5 times to confirm that there are no problems with the unit, and the flywheel is at the top dead center position after the rotation is completed.

[0060] 3) Measure and adjust the valve clearance of the cold engine: 0.004 in for the intake valve and 0.014 in for the exhaust valve.

[0061] 4) Check the coolant level inside the jacket; it should be 3-4 cm high.

[0062] 5) Read the atmospheric pressure and perform atmospheric pressure compensation according to the following formula.

[0063] Y = X * 29.92 / 101.3

[0064] X represents the atmospheric pressure during the test, in kPa.

[0065] Y represents the corrected atmospheric pressure, in Hg.

[0066] For example, the atmospheric pressure in Kunming is 81.0 kPa, and the corrected atmospheric pressure is 23.9 in Hg. Referring to Table D.4 of standard GB / T5487-2015, which provides compensation for cylinder height and corresponding temperature changes for atmospheric pressures below 101.3 kPa (29.92 in Hg), the counter correction value for 23.9 in Hg is found to be 169, with an intake temperature of 60℉. The cylinder height is adjusted so that the upper counter is 169 greater than the lower counter to perform atmospheric pressure compensation.

[0067] 5) Connect the power supply. The engine lubricating oil temperature is 135±15℉. Start the engine, turn on the cooling device and intake device, turn on the knock sensor switch and temperature control switch, turn on the ignition switch, and supply preheated fuel.

[0068] 6) Warm up the engine for about 30 minutes and check that the engine meets the following requirements: engine speed is 600±6 r / min, ignition advance angle is 13.0°, lubricating oil pressure is 25-30 Ibf / in2, coolant temperature is 212±3℉, and intake air temperature is 60℉.

[0069] 2. Determine the standard knock intensity

[0070] To determine the research octane number (ROC) of a 92-octane gasoline sample, use a standard fuel with an ROC of 93.0 to supply fuel to the engine. Adjust the compression ratio until the gauge reading reaches 770. Adjust the standard fuel level and uniformly change the fuel-air ratio to obtain the maximum knock ratio. At the maximum knock fuel-air ratio, adjust the knock meter to a reading of 50 ± 2, which represents the standard knock of the 93.0 standard fuel. When the compression ratio is changed to an octane number of 94.0, the gauge reading reaches 787. Observe the change in the knock meter pointer. If the change is between 12 and 15, the engine width is appropriate. If the change exceeds this range, reset the width to meet the 12-15 range.

[0071] 3. Engine calibrated with toluene standard fuel

[0072] Select 93.4 toluene standard fuel to supply the engine. Adjust the compression ratio to a knock gauge reading of 50. At the maximum knock fuel-air ratio, without changing the positive knock intensity reading on the knock gauge, adjust the compression ratio to a knock gauge reading of 50 ± 2. At this point, the counter reading is 764, corresponding to a research octane number (ROC) of 92.6. According to the compensation calculation formula for the ROC determination method of automotive gasoline under low pressure, ΔR = -0.08 × P + 7.25 and R = R1 + ΔR, the octane number compensation value is 0.77 units under the atmospheric pressure of 81.0 kPa during the test. Therefore, under the test conditions, the compensated R value of 93.4 toluene standard fuel is 93.4, and the deviation between the compensated measured value and the standard value is 0.0, which meets the requirement of ±0.3. The engine can be tested.

[0073] 4. Testing of automotive gasoline samples

[0074] A 92-octane gasoline sample was selected to supply fuel to the engine. The compression ratio was changed to achieve a knock gauge reading of 50. Under the maximum knock fuel-air ratio, the compression ratio was readjusted to achieve a knock gauge reading of 50 ± 2 and a counter reading of 750. Referring to the standard knock intensity operation table, the corresponding research octane number (ROC) for the compression ratio was 91.7. Using the compensation calculation formulas ΔR = -0.08 × P + 7.25 and R = R1 + ΔR for the low-pressure ROC determination of gasoline, the octane number compensation value was found to be 0.77 units under the atmospheric pressure of 81.0 kPa. The ROC value R of the 92-octane gasoline sample after compensation was 92.5, consistent with the 92.5 octane number measured under normal atmospheric pressure.

[0075] 5. Engine stopped

[0076] Close the fuel valve, drain the fuel from the fuel cup, turn off the heating and ignition switches, run the engine for 1 minute, turn off the engine switch, turn off the cooling and intake devices, rotate the engine 4-5 times to stop the flywheel at the top dead center of the compression stroke, and disconnect the main power supply.

[0077] Examples 2-16:

[0078] Tests were conducted on samples of 92-octane, 95-octane, and 98-octane automotive gasoline from the same batch at atmospheric pressures of 101.6 kPa, 88.0 kPa, 84.3 kPa, 80.0 kPa, and 77.0 kPa. The test results are shown in Table 1. Figure 1 As shown in Table 1, the measurement results exhibit good consistency. Figure 1 The table presents a comparison of the compensated research octane numbers (ROCs) measured using the compensation method of this invention at atmospheric pressures of 88.0 kPa, 84.3 kPa, 80.0 kPa, and 77.0 kPa with the ROC data measured at 101.6 kPa. (See Table 1 and...) Figure 1 As can be seen, the research octane numbers of the 92, 95, and 98 octane gasoline samples, after compensation using the method described in this invention at atmospheric pressures of 88.0 kPa, 84.3 kPa, 80.0 kPa, and 77.0 kPa respectively, showed a deviation of only 0 to 0.1 units compared to the value measured at normal atmospheric pressure of 101.6 kPa. The measurement results showed good consistency (currently, in this field, the deviation of research octane numbers measured using the standard GB / T 5487-2015 method is generally less than 0.7 units).

[0079] Table 1. Results of Octane Number Determination by Study Method under Different Atmospheric Pressures in Examples

[0080]

[0081]

[0082] The octane number compensation method and the method for determining the research octane number (ROC) of gasoline samples proposed in this invention study and analyze the variation law of ROC determination results for automotive gasoline under low pressure, especially under conditions of 77.0–88.0 kPa. It summarizes and establishes the correspondence between atmospheric pressure and the change of the ROC compensation value. This is the first systematic study of ROC determination under low pressure both domestically and internationally. This invention effectively supplements existing ROC determination techniques, improving the accuracy of ROC determination results for automotive gasoline under low pressure (especially at atmospheric pressures of 77.0–88.0 kPa). This invention can systematically reflect the accurate compensation of ROC determination results for automotive gasoline under low pressure environments, improving the accuracy of ROC determination results for automotive gasoline in low-pressure areas, and providing a basis for quality control of automotive gasoline in low-pressure areas.

[0083] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for compensating for the octane number of a research method under low pressure, characterized in that, The compensated research octane number R of the sample is the research octane number R1 plus the compensated research octane number ΔR of the sample, with the formula: R = R1 + ΔR; the compensated research octane number ΔR of the sample is -0.08 × P + 7.25, where P is the atmospheric pressure during the test, and its unit is kPa; the research octane number R1 is determined according to the method in standard GB / T 5487-2015; the atmospheric pressure during the test is 77.0~88.0 kPa.

2. A method for determining octane number under low pressure, characterized in that, The steps include: (i) inspecting the engine; (ii) determining the standard knock intensity; (iii) calibrating the engine with toluene standard fuel; and (iv) measuring gasoline samples. Among them, step (ii) is executed first and then step (iii), or step (iii) is executed first and then step (ii). In steps (iii) and (iv), the compensation method as described in claim 1 is used to compensate for the research octane number.

3. The method for determining octane number under low pressure according to claim 2, characterized in that, The method for calibrating an engine using toluene standard fuel is as follows: An engine suitability test is conducted using toluene standard fuel with an octane number within the range required by the standard GB / T 5487-2015, matching that of the gasoline sample. The toluene standard fuel is selected to supply fuel to the engine. The compression ratio is adjusted until the knock gauge reading is 50. At the maximum knock fuel-air ratio, without changing the positive knock intensity reading on the knock gauge, the compression ratio is adjusted until the knock gauge reading is 50±2. The research octane number (ROC) of the toluene standard fuel is obtained from the standard knock intensity operation table. The R of the toluene standard fuel after compensation under the test atmospheric pressure conditions is calculated using the formulas ΔR=-0.08×P+7.25 and R=R1+ΔR. The compensated R of the toluene standard fuel is then compared with the standard value of the toluene standard fuel to check for engine measurement deviations.

4. The method for determining octane number under low pressure according to claim 2, characterized in that, The method for determining the gasoline sample is as follows: Select a gasoline sample to supply fuel to the engine, change the compression ratio to make the knock gauge reading 50, and at the maximum knock fuel-air ratio, readjust the compression ratio to make the knock gauge reading 50±2. Read the counter reading, look up the corresponding research octane number of the compression ratio in the standard knock intensity operation table, and calculate the research octane number of the gasoline sample after compensation under the test atmospheric pressure conditions according to the formulas ΔR=-0.08×P+7.25 and R=R1+ΔR. This is the final research octane number of the gasoline sample.

5. The method for determining octane number under low pressure according to claim 2, characterized in that, The method for determining the standard knock intensity is as follows: select a positive standard fuel with an octane number within the range required by the standard GB / T 5487-2015 that matches the octane number of the sample gasoline, supply fuel to the engine, change the compression ratio to the value required by the operating table, and adjust the knock meter to make the reading 50±2 under the maximum knock fuel-air ratio.

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