Marine low-speed engine and compression ratio adjusting method thereof

Abstract

The invention discloses a marine low-speed engine and a compression ratio adjusting method thereof, and the method comprises the steps: determining an initial geometric compression ratio of the engine based on an engine load and an operation mode of the engine; in the operation mode, operation parameters of the engine in the current environment are obtained; determining the correction of the geometric compression ratio of the engine according to the operating parameters; and according to the correction and the initial geometric compression ratio, the target compression ratio of the engine is determined, and the engine is adjusted to the target compression ratio. By means of the method, adjustment of the compression ratio of the engine in the current environment is achieved, the compression ratio of the engine is adjusted to the target compression ratio, energy consumption of the engine is optimized, and stable operation of the engine is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine low-speed engines, and particularly relates to a marine low-speed engine and a compression ratio adjusting method thereof. BACKGROUND

[0002] The engine with variable compression ratio breaks through the design of traditional engines with fixed compression ratio, and can adjust the compression ratio under the load in real time according to the operation mode of the engine and the change of the working condition.

[0003] The traditional marine low-speed engine is designed with fixed compression ratio, and cannot adjust the compression ratio in real time according to the change of the working condition, so that the engine cannot always maintain the best performance under different loads and environmental conditions. Although the concept of the engine with variable compression ratio exists in the prior art, there is still a lack of specific optimization method for the marine low-speed engine, especially how to dynamically adjust the compression ratio according to the environmental parameters and the combustion condition. SUMMARY

[0004] The present application provides a marine low-speed engine and a compression ratio adjusting method thereof, so as to adjust the compression ratio of the engine under the current environment according to the operation parameters under the current environment, and adjust the compression ratio of the engine to the target compression ratio, thereby continuously optimizing the performance of the engine during operation and ensuring the stable operation of the engine under different modes.

[0005] In a first aspect, the present application provides a compression ratio adjusting method of a marine low-speed engine, comprising:

[0006] determining an initial geometric compression ratio of the engine based on the load of the engine and the operation mode of the engine;

[0007] obtaining operation parameters of the engine under the current environment in the operation mode;

[0008] determining a correction amount of the geometric compression ratio of the engine according to the operation parameters;

[0009] determining a target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjusting the engine to the target compression ratio.

[0010] Optionally, after determining the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and before adjusting the engine to the target compression ratio, the method further comprises:

[0011] determining that the target compression ratio is out of the first preset condition.

[0012] Optionally, the target compression ratio is V1, and the initial geometric compression ratio is V2.

[0013] The first preset condition comprises 0.95V2≤V1≤1.05V2, and V1≤V1_min or V1≥V1_max;

[0014] V1_min is the minimum geometric compression ratio of the engine under mechanical limit, and V1_max is the maximum geometric compression ratio of the engine under mechanical limit.

[0015] Optionally, the operation mode of the engine comprises a fuel mode; and the operation parameter comprises a scavenging temperature, an atmospheric pressure, a supercharger intake temperature, a fuel quality parameter, and a cylinder explosion pressure.

[0016] According to the operation parameter, a correction amount of the geometric compression ratio of the engine is determined, comprising:

[0017] Based on the scavenging temperature, a correction amount of the scavenging temperature on the geometric compression ratio of the engine is determined.

[0018] Based on the atmospheric pressure, a correction amount of the atmospheric pressure on the geometric compression ratio of the engine is determined.

[0019] Based on the supercharger intake temperature, a correction amount of the supercharger intake temperature on the geometric compression ratio of the engine is determined.

[0020] Based on the fuel quality parameter, a correction amount of the fuel quality parameter on the geometric compression ratio of the engine is determined.

[0021] Based on the cylinder explosion pressure, a correction amount of the cylinder explosion pressure on the geometric compression ratio of the engine is determined.

[0022] Optionally, based on the scavenging temperature, a correction amount of the scavenging temperature on the geometric compression ratio of the engine is determined, comprising:

[0023] Based on the scavenging temperature, a ratio of the scavenging temperature to a preset scavenging temperature reference value is multiplied by a geometric compression ratio parameter change amount corresponding to the scavenging temperature, to determine a correction amount of the scavenging temperature on the geometric compression ratio of the engine; and / or,

[0024] Based on the atmospheric pressure, a correction amount of the atmospheric pressure on the geometric compression ratio of the engine is determined, comprising:

[0025] Based on the atmospheric pressure, a ratio of the atmospheric pressure to a preset atmospheric pressure reference value is multiplied by a geometric compression ratio parameter change amount corresponding to the atmospheric pressure, to determine a correction amount of the atmospheric pressure on the geometric compression ratio of the engine; and / or,

[0026] Based on the supercharger intake temperature, a correction amount of the supercharger intake temperature on the geometric compression ratio of the engine is determined, comprising:

[0027] determining a correction amount of the turbocharger intake temperature to the engine geometric compression ratio based on the turbocharger intake temperature, including:

[0028] determining a correction amount of the fuel quality parameter to the engine geometric compression ratio based on the fuel quality parameter, including:

[0029] determining a correction amount of the turbocharger intake temperature to the engine geometric compression ratio based on the turbocharger intake temperature, including:

[0030] determining a correction amount of the cylinder pressure to the engine geometric compression ratio based on the cylinder pressure, including:

[0031] determining a correction amount of the cylinder pressure to the engine geometric compression ratio based on the cylinder pressure, including:

[0032] Optionally, the cylinder pressure is P1, and the preset cylinder pressure reference value is P2.

[0033] determining a correction amount of the cylinder pressure to the engine geometric compression ratio based on the cylinder pressure, including:

[0034] determining that the cylinder pressure is not in the second preset condition; the second preset condition is P2-3 bar≤P1≤P2+3 bar.

[0035] Optionally, the operation mode of the engine includes a gas mode; the operation parameters include a scavenging temperature, an atmospheric pressure, a turbocharger intake temperature, a fuel low heat value parameter, a gas methane value, and a cylinder pressure change gradient.

[0036] determining a correction amount of the engine geometric compression ratio according to the operation parameters, including:

[0037] determining a correction amount of the scavenging temperature to the engine geometric compression ratio based on the scavenging temperature;

[0038] determining a correction amount of the atmospheric pressure to the engine geometric compression ratio based on the atmospheric pressure;

[0039] determining a correction amount of the turbocharger intake temperature to the engine geometric compression ratio based on the turbocharger intake temperature;

[0040] determining a correction amount of the fuel low heat value parameter to the engine geometric compression ratio based on the fuel low heat value parameter;

[0041] determining a correction amount of the gas methane value to the engine geometric compression ratio based on the gas methane value;

[0042] determining a correction amount of the cylinder explosion pressure change gradient to the engine geometric compression ratio based on the cylinder explosion pressure change gradient.

[0043] Optionally, determining a correction amount of the scavenging temperature to the engine geometric compression ratio based on the scavenging temperature, comprising:

[0044] determining a correction amount of the scavenging temperature to the engine geometric compression ratio based on the scavenging temperature, comprising:

[0045] determining a correction amount of the atmospheric pressure to the engine geometric compression ratio based on the atmospheric pressure, comprising:

[0046] determining a correction amount of the atmospheric pressure to the engine geometric compression ratio based on the atmospheric pressure, comprising:

[0047] determining a correction amount of the supercharger intake temperature to the engine geometric compression ratio based on the supercharger intake temperature, comprising:

[0048] determining a correction amount of the supercharger intake temperature to the engine geometric compression ratio based on the supercharger intake temperature, comprising:

[0049] determining a correction amount of the fuel low heat value parameter to the engine geometric compression ratio based on the fuel low heat value parameter, comprising:

[0050] determining a correction amount of the fuel low heat value parameter to the engine geometric compression ratio based on the fuel low heat value parameter, comprising:

[0051] determining a correction amount of the gas methane value to the engine geometric compression ratio based on the gas methane value, comprising:

[0052] determining a correction amount of the gas methane value to the engine geometric compression ratio based on the gas methane value, comprising:

[0053] determining a correction amount of the cylinder explosion pressure change gradient to the engine geometric compression ratio based on the cylinder explosion pressure change gradient, comprising:

[0054] Based on the cylinder pressure change gradient, the ratio of the cylinder pressure change gradient to the preset cylinder pressure change gradient reference value is multiplied by the geometric compression ratio parameter change corresponding to the cylinder pressure change gradient to determine the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio.

[0055] Optionally, the cylinder pressure change gradient is dP1, and the preset cylinder pressure change gradient reference value is dP2.

[0056] Before determining the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio based on the cylinder pressure change gradient, the ratio of the cylinder pressure change gradient to the preset cylinder pressure change gradient reference value is multiplied by the geometric compression ratio parameter change corresponding to the cylinder pressure change gradient, the method further comprises:

[0057] Determine that the cylinder pressure change gradient is outside the third preset condition; the third preset condition is 0.8dP2≤dP1≤1.2dP2.

[0058] Optionally, according to the correction amount and the initial geometric compression ratio, the target compression ratio of the engine is determined, comprising:

[0059] According to the correction amount and the initial geometric compression ratio, the target compression ratio of the engine is determined based on the first calculation formula.

[0060] The first calculation formula is: V1=V2×(1+V3), V1 is the target compression ratio, V2 is the initial geometric compression ratio, and V3 is the correction amount.

[0061] In a second aspect, the present application provides a marine low-speed engine, which adopts the compression ratio adjusting method of the marine low-speed engine.

[0062] The technical scheme of the present application determines the initial geometric compression ratio of the engine based on the engine load and the operating mode of the engine; obtains the operating parameters of the engine under the current environment in the operating mode; determines the correction amount of the engine geometric compression ratio according to the operating parameters; determines the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjusts the engine to the target compression ratio. By using the above method, the correction amount of the engine compression ratio is determined according to the operating parameters of the engine under the environment, the performance optimization of the engine in the full working condition range is realized, the economy and stability of the ship operation are ensured, and the service life of the engine is prolonged.

[0063] It should be understood that the contents described in this part are not intended to identify the key or important features of the embodiments of the present application, nor are they used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to make the technical solution in the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0065] Figure 1 is a flow chart of a compression ratio adjusting method of a marine low-speed engine provided by an embodiment of the present application;

[0066] Figure 2 is a flow chart of another compression ratio adjusting method of a marine low-speed engine provided by an embodiment of the present application;

[0067] Figure 3 is a flow chart of still another compression ratio adjusting method of a marine low-speed engine provided by an embodiment of the present application;

[0068] Figure 4 is a flow chart of another compression ratio adjusting method of a marine low-speed engine provided by an embodiment of the present application. DETAILED DESCRIPTION

[0069] In order to make the technical solution in the embodiments of the present application clearer, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0070] It should be noted that the terms "first", "second", and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to include all the steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0071] In an embodiment, Figure 1 is a flow chart of a compression ratio adjusting method of a marine low-speed engine provided by an embodiment of the present application, and the present embodiment can be applied to the case of adjusting the compression ratio of the engine in real time according to the current environmental operating parameters, such asFigure 1 The method comprises:

[0072] S110, determining an initial geometric compression ratio of the engine based on an engine load and an operation mode of the engine.

[0073] The engine load refers to the ratio of the power output by the engine at a certain moment to the maximum power that the engine can achieve at the current speed, usually expressed in percentage, such as 25%, 50% or 100% load, etc. The engine operation mode refers to the working interval or control strategy state divided according to the working conditions (speed, load, temperature, driving demand, etc.). In this embodiment, the operation mode of the engine includes at least a gas mode and a fuel mode. The geometric compression ratio is the ratio of the total volume of the cylinder (piston at bottom dead center) to the volume of the combustion chamber (piston at top dead center).

[0074] Specifically, when determining the initial geometric compression ratio of the engine, the engine load and the operation mode of the engine can be determined first, wherein the engine load can be determined according to signals such as throttle opening, speed and torque. The engine operation mode can be determined according to the mode in which the engine is operated, which can be determined according to actual conditions and is not limited herein. After the engine load and the operation mode of the engine are determined, the geometric compression ratio of the engine corresponding to the load and the operation mode can be determined through a bench test according to the test conditions, and the compression ratio is taken as the initial geometric compression ratio.

[0075] S120, obtaining an operation parameter of the engine under the current environment in the operation mode.

[0076] The operation parameter under the current environment is a parameter reflecting the current operation state of the engine, and in this embodiment, the operation parameters corresponding to different engine operation modes can be different. Exemplary operation parameters can include but are not limited to scavenging temperature, atmospheric pressure and supercharger intake temperature, etc.

[0077] Specifically, according to the operation mode of the engine, the corresponding operation parameter under the current environment in different operation modes is obtained, wherein the operation parameter can be obtained by means such as sensors, etc.

[0078] S130, determining a correction amount of the geometric compression ratio of the engine according to the operation parameter.

[0079] The correction amount is the amount determined to adjust the geometric compression ratio of the engine.

[0080] Specifically, when the correction amount of the geometric compression ratio is determined according to the operating parameter, the correction amount of the geometric compression ratio of the engine can be determined according to the corresponding relationship between the operating parameter and the correction amount of the geometric compression ratio, that is, after the operating parameter is determined, the correction amount of the geometric compression ratio of the engine can be determined according to the operating parameter through the corresponding relationship. In addition, in addition to the above-mentioned preset corresponding relationship, the correction amount of the geometric compression ratio can also be determined through other logical calculation or the like, which is not limited here.

[0081] S140, determine the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjust the engine to the target compression ratio.

[0082] The target compression ratio is the final compression ratio that needs to be reached during the operation of the engine, and the engine can be normally and stably operated at the target compression ratio.

[0083] Specifically, after the correction amount of the geometric compression ratio and the initial geometric compression ratio are determined, the target compression ratio of the engine can be determined according to the correction amount and the initial geometric compression ratio through logical operation or a preset corresponding relationship, and the engine can be adjusted to the target compression ratio for stable operation.

[0084] The technical scheme of the embodiment of the application determines the initial geometric compression ratio of the engine based on the engine load and the operating mode of the engine, obtains the operating parameter of the engine under the current environment in the operating mode, determines the correction amount of the geometric compression ratio of the engine according to the operating parameter, determines the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjusts the engine to the target compression ratio. By using the above method, the correction amount of the compression ratio of the engine is determined according to the operating parameter of the engine under the environment, the performance optimization of the engine in the full operating range is realized, the economy and stability of the ship operation are ensured, and the service life of the engine is prolonged.

[0085] In another specific embodiment, Figure 2 The flowchart of another compression ratio adjustment method of a marine low-speed engine provided by the embodiment of the application, after the step S140 of determining the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio in the above-mentioned embodiment, the following steps are further added:

[0086] It is determined that the target compression ratio is out of the first preset condition.

[0087] Further, the specific implementation mode of the step S140 of determining the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio is refined as follows:

[0088] The target compression ratio of the engine is determined according to the correction amount and the initial geometric compression ratio based on the first calculation formula;

[0089] The first calculation formula is V1=V2*(1+V3), V1 is the target compression ratio, V2 is the initial geometric compression ratio, and V3 is the correction amount.

[0090] The details of the embodiment not yet described can refer to the above embodiments, which will not be described here.

[0091] Reference Figure 2 The method comprises:

[0092] S210, determining the initial geometric compression ratio of the engine based on the engine load and the operating mode of the engine.

[0093] S220, obtaining the operating parameters of the engine under the current environment in the operating mode.

[0094] S230, determining the correction amount of the geometric compression ratio of the engine according to the operating parameters.

[0095] S240, determining the target compression ratio of the engine based on the first calculation formula according to the correction amount and the initial geometric compression ratio.

[0096] Specifically, after the correction amount of the engine compression ratio and the initial geometric compression ratio are determined, the target compression ratio V1 can be calculated by substituting the correction amount V3 and the initial geometric compression ratio V2 into the first calculation formula, wherein the first calculation formula is V1=V2*(1+V3), V1 is the target compression ratio, V2 is the initial geometric compression ratio, and V3 is the correction amount.

[0097] S250, determining that the target compression ratio is outside the first preset condition, and adjusting the engine to the target compression ratio.

[0098] Specifically, after determining the target compression ratio of the engine, it is necessary to confirm the target compression ratio, determine that the target compression ratio is outside the first preset condition, and in this embodiment, the target compression ratio is V1, and the initial geometric compression ratio is V2; the first preset condition includes 0.95V2≤V1≤1.05V2, and V1≤V1_min or V1≥V1_max; wherein V1_min is the minimum geometric compression ratio of the engine under mechanical limitation, and V1_max is the maximum geometric compression ratio of the engine under mechanical limitation. That is, it is necessary to ensure that the determined target compression ratio V1 is less than 0.95 times of the initial geometric compression ratio V2, and greater than 1.05 times of V2, so that the target compression ratio V1 can be used as the final engine to reach the target compression ratio. The purpose of such setting is to achieve smooth and continuous adjustment of the engine compression ratio, and to avoid the occurrence of jamming. Moreover, the determined target compression ratio V1 cannot be the maximum or minimum geometric compression ratio under mechanical limitation, that is, V1_min<V1<V1_max, which means that the target compression ratio is effective. The purpose of such setting is to ensure that the compression ratio of the engine can be accurately adjusted to the target compression ratio, and to improve the stability of the marine engine.

[0099] The technical scheme of the embodiment of the application determines the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio based on the first calculation formula; the first calculation formula is: V1=V2×(1+V3), V1 is the target compression ratio, V2 is the initial geometric compression ratio, and V3 is the correction amount; and the target compression ratio is determined to be outside the first preset condition. By using the above method, accurate determination of the target compression ratio and smooth and continuous adjustment of the engine compression ratio are realized, and the stability of the marine low-speed engine is improved.

[0100] In another specific embodiment, Figure 3 The flowchart of another method for adjusting the compression ratio of a marine low-speed engine provided by the embodiment of the application is provided, and the specific implementation of the method S130 in the above embodiment is detailed as follows:

[0101] Based on the scavenging temperature, the correction amount of the scavenging temperature to the geometric compression ratio of the engine is determined;

[0102] Based on the atmospheric pressure, the correction amount of the atmospheric pressure to the geometric compression ratio of the engine is determined;

[0103] Based on the supercharger intake temperature, the correction amount of the supercharger intake temperature to the geometric compression ratio of the engine is determined;

[0104] Based on the fuel quality parameter, the correction amount of the fuel quality parameter to the geometric compression ratio of the engine is determined;

[0105] Based on the cylinder pressure, the correction amount of the cylinder pressure to the geometric compression ratio of the engine is determined.

[0106] The details of the embodiment not yet described can refer to the above embodiments, which will not be described here.

[0107] Reference Figure 3 As shown in the method comprises:

[0108] S310, based on the engine load and the operating mode of the engine, determining the initial geometric compression ratio of the engine.

[0109] Wherein, the operating mode of the engine includes fuel mode. In the fuel mode, such as the engine runs at 75% load, according to the parameter setting formulated in the engine bench test, the engine sends out the instruction of the default compression ratio under the load, and through the variable compression ratio device installed between the piston rod and the connecting rod, the mechanical compression ratio of the engine is adjusted to the initial geometric compression ratio under the default 75% load.

[0110] S320, in the operating mode, obtaining the operating parameters of the engine under the current environment.

[0111] Wherein, in the fuel mode, the operating parameters include scavenging temperature, atmospheric pressure, supercharger intake temperature, fuel quality parameters and cylinder explosion pressure. Scavenging temperature can be obtained by but not limited to scavenging temperature sensor, which is installed on the engine scavenging tank, and is preferably installed at a position that can reflect the average temperature of the engine scavenging tank. Atmospheric pressure can be obtained by but not limited to atmospheric pressure gauge, which is installed at the engine cabin position. The supercharger intake temperature can be obtained by but not limited to the supercharger intake temperature sensor, which is installed at the air suction position of the supercharger, and is preferably installed at a position that can reflect the actual supercharger intake temperature. The fuel quality parameters can be obtained by fuel test report and other methods. The cylinder explosion pressure can be obtained by but not limited to the explosion pressure sensor, which is installed on each cylinder of the engine.

[0112] S330, based on the scavenging temperature, determining the correction amount of the scavenging temperature to the geometric compression ratio of the engine.

[0113] Wherein, this step can be refined as: based on the scavenging temperature, multiplying the ratio of the scavenging temperature to the preset scavenging temperature reference value with the geometric compression ratio parameter change corresponding to the scavenging temperature, to determine the correction amount of the scavenging temperature to the geometric compression ratio of the engine.

[0114] Specifically, after the scavenging temperature is obtained, the scavenging temperature is divided by a preset scavenging temperature reference value to obtain a ratio of the two, and the ratio is multiplied by a geometric compression ratio parameter change corresponding to the scavenging temperature, so that a correction amount of the scavenging temperature on the engine geometric compression ratio can be obtained. The preset scavenging temperature reference value is a scavenging temperature reference value under the current load of the engine, and the acquisition manner can directly determine the preset scavenging temperature reference value under the current load from the scavenging pressure reference values under different loads specified in the engine factory. The acquisition manner of the scavenging temperature and the geometric compression ratio parameter change corresponding to the scavenging temperature can be determined according to the scavenging temperature parameter change corresponding relationship specified when the engine is factory-fitted, or can be determined and corrected through actual experimental conditions.

[0115] S340, based on the atmospheric pressure, determining a correction amount of the atmospheric pressure on the engine geometric compression ratio.

[0116] The step can be refined as: based on the atmospheric pressure, multiplying the ratio of the atmospheric pressure and a preset atmospheric pressure reference value by a preset atmospheric pressure change to determine a corrected correction atmospheric pressure.

[0117] Specifically, after the atmospheric pressure is obtained, the atmospheric pressure is divided by a preset atmospheric pressure reference value to obtain a ratio of the two, and the ratio is multiplied by a geometric compression ratio parameter change corresponding to the atmospheric pressure, so that a correction amount of the atmospheric pressure on the engine geometric compression ratio can be obtained. The preset atmospheric pressure reference value is an atmospheric pressure reference value under the current load of the engine, and the acquisition manner can directly determine the preset atmospheric pressure reference value under the current load from the scavenging pressure reference values under different loads specified in the engine factory. In this embodiment, the preset atmospheric pressure reference value can be 1000 hPa. The acquisition manner of the atmospheric pressure and the geometric compression ratio parameter change corresponding to the atmospheric pressure can be determined according to the atmospheric pressure parameter change corresponding relationship specified when the engine is factory-fitted, or can be determined and corrected through actual experimental conditions.

[0118] S350, based on the supercharger intake temperature, determining a correction amount of the supercharger intake temperature on the engine geometric compression ratio.

[0119] The step can be refined as: based on the supercharger intake temperature, multiplying the ratio of the supercharger intake temperature and a preset supercharger intake temperature reference value by a geometric compression ratio parameter change corresponding to the supercharger intake temperature to determine a correction amount of the supercharger intake temperature on the engine geometric compression ratio.

[0120] Specifically, after the supercharger intake temperature is obtained, the supercharger intake temperature is divided by the preset supercharger intake temperature reference value to obtain a ratio, and the ratio is multiplied by the geometric compression ratio parameter change corresponding to the supercharger intake temperature, so that the correction amount of the supercharger intake temperature on the engine geometric compression ratio can be obtained. The preset supercharger intake temperature reference value is the supercharger intake temperature reference value under the current load of the engine, and the obtaining method can directly determine the preset supercharger intake temperature reference value under the current load from the scavenging pressure reference values under different loads specified in the engine factory. In this embodiment, the preset supercharger intake temperature reference value can be 25℃. The obtaining method of the geometric compression ratio parameter corresponding to the supercharger intake temperature can be determined according to the parameter change corresponding relationship of the supercharger intake temperature specified when the engine is factory-fitted, or can be determined and corrected through actual experimental conditions.

[0121] S360, determining a correction amount of the fuel quality parameter on the engine geometric compression ratio based on the fuel quality parameter.

[0122] The step can be further refined as follows: based on the fuel quality parameter, multiplying the ratio of the fuel quality parameter to the preset fuel quality parameter reference value by the geometric compression ratio parameter change corresponding to the fuel quality parameter to determine the correction amount of the fuel quality parameter on the engine geometric compression ratio.

[0123] Specifically, after the fuel quality parameter is obtained, the fuel quality parameter is divided by the preset fuel quality parameter reference value to obtain a ratio, and the ratio is multiplied by the geometric compression ratio parameter change corresponding to the fuel quality parameter, so that the correction amount of the fuel quality parameter on the engine geometric compression ratio can be obtained. The preset fuel quality parameter reference value is the fuel quality parameter reference value under the current load of the engine, and the obtaining method can directly determine the preset fuel quality parameter reference value from the fuel quality parameter reference values specified in the engine factory. In this embodiment, the preset fuel quality parameter reference value is 42700kJ / kg. The obtaining method of the geometric compression ratio parameter corresponding to the fuel quality parameter can be determined according to the parameter change corresponding relationship of the fuel quality parameter specified when the engine is factory-fitted, or can be determined and corrected through actual experimental conditions.

[0124] S370, determining a correction amount of the cylinder explosion pressure on the engine geometric compression ratio based on the cylinder explosion pressure.

[0125] The step can be further refined as follows: based on the cylinder explosion pressure, multiplying the ratio of the cylinder explosion pressure to the preset cylinder explosion pressure reference value by the geometric compression ratio parameter change corresponding to the cylinder explosion pressure to determine the correction amount of the cylinder explosion pressure on the engine geometric compression ratio.

[0126] Specifically, after the cylinder explosion pressure is obtained, the cylinder explosion pressure is divided by a preset cylinder explosion pressure reference value to obtain a ratio of the two, and the ratio is multiplied by a geometric compression ratio parameter change corresponding to the cylinder explosion pressure, so that a correction amount of the cylinder explosion pressure on the engine geometric compression ratio can be obtained. The preset cylinder explosion pressure reference value is a cylinder explosion pressure reference value under the current load of the engine, and the acquisition method can directly determine the preset cylinder explosion pressure reference value under the current load from the load and the operation mode of the engine. The acquisition method of the geometric compression ratio parameter change corresponding to the cylinder explosion pressure can be determined according to the cylinder explosion pressure parameter change corresponding relationship specified when the engine is shipped, or can be determined and corrected through actual experimental conditions.

[0127] S380, determining the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjusting the engine to the target compression ratio.

[0128] The technical scheme of the embodiment of the application determines the correction amount of the scavenging temperature on the engine geometric compression ratio based on the scavenging temperature, determines the correction amount of the atmospheric pressure on the engine geometric compression ratio based on the atmospheric pressure, determines the correction amount of the supercharger intake temperature on the engine geometric compression ratio based on the supercharger intake temperature, determines the correction amount of the fuel quality parameter on the engine geometric compression ratio based on the fuel quality parameter, determines the correction amount of the cylinder explosion pressure on the engine geometric compression ratio based on the cylinder explosion pressure, and determines the correction amount of the engine geometric compression ratio according to the scavenging temperature, the atmospheric pressure, the supercharger intake temperature, the fuel quality parameter and the cylinder explosion pressure. By using the above method, the determination of the correction amount of the engine geometric compression ratio in the fuel mode is realized, which provides a basis for subsequent determination of the target compression ratio based on the correction amount, and improves the economy and stability of the engine operation.

[0129] Optionally, the cylinder explosion pressure is P1, and the preset cylinder explosion pressure reference value is P2; before the ratio of the cylinder explosion pressure to the preset cylinder explosion pressure reference value is multiplied by the geometric compression ratio parameter change corresponding to the cylinder explosion pressure to determine the correction amount of the cylinder explosion pressure on the engine geometric compression ratio based on the cylinder explosion pressure, it further includes: determining that the cylinder explosion pressure is outside a second preset condition; the second preset condition is P2-3 bar≤P1≤P2+3 bar.

[0130] Specifically, after obtaining the cylinder explosion pressure of the engine, the cylinder explosion pressure needs to be first confirmed, and when it is determined that the cylinder explosion pressure is outside the second preset condition, the correction amount of the engine geometric compression ratio corresponding to the cylinder explosion pressure can be determined according to the cylinder explosion pressure. In the embodiment, the second preset condition is P2-3 bar≤P1≤P2+3 bar, that is, when the cylinder explosion pressure P1 is within the above range, the cylinder explosion pressure is not used as a parameter for correcting the engine geometric compression ratio, and only when P1 is outside the above range, the cylinder explosion pressure can be used as a parameter for correcting the engine geometric compression ratio, and the correction amount of the engine geometric compression ratio is determined based on the cylinder explosion pressure. The reason for such setting is that when the cylinder explosion pressure is within the above range, it indicates that the current cylinder explosion pressure is within the normal fluctuation range, and there is no need to adjust through the explosion pressure feedback, avoiding unnecessary frequent adjustment.

[0131] In another specific embodiment, Figure 4 The flowchart of another method for adjusting the compression ratio of a marine low-speed engine is provided in the embodiment of the application, and the specific implementation of S130, determining the correction amount of the engine geometric compression ratio according to the operating parameters, is refined as follows:

[0132] determining the correction amount of the engine geometric compression ratio by the scavenging temperature based on the scavenging temperature;

[0133] determining the correction amount of the engine geometric compression ratio by the atmospheric pressure based on the atmospheric pressure;

[0134] determining the correction amount of the engine geometric compression ratio by the supercharger intake temperature based on the supercharger intake temperature;

[0135] determining the correction amount of the engine geometric compression ratio by the low heat value of fuel based on the low heat value of fuel;

[0136] determining the correction amount of the engine geometric compression ratio by the methane value of fuel gas based on the methane value of fuel gas;

[0137] determining the correction amount of the engine geometric compression ratio by the cylinder explosion pressure gradient based on the cylinder explosion pressure gradient.

[0138] The details of the embodiment not yet described can refer to the above embodiments, which will not be described here.

[0139] Reference Figure 4 The method comprises:

[0140] S410, determining the initial geometric compression ratio of the engine based on the engine load and the operating mode of the engine.

[0141] The operation mode of the engine includes a gas mode. In the gas mode, when the engine operates at 75% load, according to the parameter setting in the engine bench test, the engine issues an instruction of a default geometric compression ratio at the load, and the mechanical compression ratio of the engine is adjusted to the initial geometric compression ratio at the default 75% load through the variable compression ratio device installed between the piston rod and the connecting rod.

[0142] In the operation mode, an operation parameter of the engine under a current environment is acquired.

[0143] In the gas mode, the operation parameter of the engine includes a scavenging temperature, an atmospheric pressure, a supercharger intake temperature, a fuel low heat value parameter, a gas methane value and a cylinder explosion pressure change gradient. The scavenging temperature can be acquired by but not limited to a scavenging temperature sensor, which is installed on the engine scavenging tank and is preferably installed at a position that can reflect the average temperature of the engine scavenging tank. The atmospheric pressure can be acquired by but not limited to an atmospheric pressure gauge, which is installed at a position of the engine cabin. The supercharger intake temperature can be acquired by but not limited to a supercharger intake temperature sensor, which is installed at the air suction position of the supercharger and is preferably installed at a position that can reflect the actual supercharger intake temperature. The fuel low heat value parameter and the gas methane value can be acquired by a fuel test report and the like. The cylinder explosion pressure change gradient can be acquired by but not limited to an explosion pressure sensor, which is installed on each cylinder of the engine.

[0144] In the operation mode, an operation parameter of the engine under a current environment is acquired.

[0143] In the gas mode, the operation parameter of the engine includes a scavenging temperature, an atmospheric pressure, a supercharger intake temperature, a fuel low heat value parameter, a gas methane value and a cylinder explosion pressure change gradient. The scavenging temperature can be acquired by but not limited to a scavenging temperature sensor, which is installed on the engine scavenging tank and is preferably installed at a position that can reflect the average temperature of the engine scavenging tank. The atmospheric pressure can be acquired by but not limited to an atmospheric pressure gauge, which is installed at a position of the engine cabin. The supercharger intake temperature can be acquired by but not limited to a supercharger intake temperature sensor, which is installed at the air suction position of the supercharger and is preferably installed at a position that can reflect the actual supercharger intake temperature. The fuel low heat value parameter and the gas methane value can be acquired by a fuel test report and the like. The cylinder explosion pressure change gradient can be acquired by but not limited to an explosion pressure sensor, which is installed on each cylinder of the engine.

[0144] S430, based on the scavenging temperature, determining a correction amount of the scavenging temperature to the geometric compression ratio of the engine.

[0145] In this step, based on the scavenging temperature, the ratio of the scavenging temperature to the preset scavenging temperature reference value is multiplied by the geometric compression ratio parameter change amount corresponding to the scavenging temperature to determine the correction amount of the scavenging temperature to the geometric compression ratio of the engine.

[0146] Specifically, after the scavenging temperature is acquired, the scavenging temperature is divided by the preset scavenging temperature reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change amount corresponding to the scavenging temperature, so that the correction amount of the scavenging temperature to the geometric compression ratio of the engine can be obtained. The preset scavenging temperature reference value is the scavenging temperature reference value under the current load of the engine, which can be directly determined from the different load scavenging pressure reference values specified in the engine factory. The acquisition method of the geometric compression ratio parameter change amount corresponding to the scavenging temperature can be determined according to the scavenging temperature parameter change corresponding relationship specified when the engine is manufactured, or can be determined and corrected through actual experimental conditions.

[0147] S440, based on the atmospheric pressure, determining a correction amount of the atmospheric pressure to the geometric compression ratio of the engine.

[0148] The step can be further divided into: based on the atmospheric pressure, multiplying the ratio of the atmospheric pressure to the preset atmospheric pressure reference value by the geometric compression ratio parameter change corresponding to the atmospheric pressure to determine the correction amount of the atmospheric pressure to the engine geometric compression ratio.

[0149] Specifically, after obtaining the atmospheric pressure, the atmospheric pressure is divided by the preset atmospheric pressure reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change corresponding to the atmospheric pressure, so that the correction amount of the atmospheric pressure to the engine geometric compression ratio can be obtained. The preset atmospheric pressure reference value is the atmospheric pressure reference value under the current load of the engine, and the acquisition method can directly determine the preset atmospheric pressure reference value under the current load from the scavenging pressure reference values under different loads specified by the engine manufacturer. In this embodiment, the preset atmospheric pressure reference value can be 1000 hPa. The acquisition method of the geometric compression ratio parameter change corresponding to the atmospheric pressure can be determined according to the atmospheric pressure parameter change corresponding relationship specified by the engine manufacturer when the engine is manufactured, or can be determined and corrected through actual experimental conditions.

[0150] S450, based on the supercharger intake temperature, determining the correction amount of the supercharger intake temperature to the engine geometric compression ratio.

[0151] The step can be further divided into: based on the supercharger intake temperature, multiplying the ratio of the supercharger intake temperature to the preset supercharger intake temperature reference value by the geometric compression ratio parameter change corresponding to the supercharger intake temperature to determine the correction amount of the intake temperature to the engine geometric compression ratio.

[0152] Specifically, after obtaining the supercharger intake temperature, the supercharger intake temperature is divided by the preset supercharger intake temperature reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change corresponding to the supercharger intake temperature, so that the correction amount of the supercharger intake temperature to the engine geometric compression ratio can be obtained. The preset supercharger intake temperature reference value is the supercharger intake temperature reference value under the current load of the engine, and the acquisition method can directly determine the preset supercharger intake temperature reference value under the current load from the scavenging pressure reference values under different loads specified by the engine manufacturer. In this embodiment, the preset supercharger intake temperature reference value can be 25℃. The acquisition method of the geometric compression ratio parameter change corresponding to the supercharger intake temperature can be determined according to the supercharger intake temperature parameter change corresponding relationship specified by the engine manufacturer when the engine is manufactured, or can be determined and corrected through actual experimental conditions.

[0153] S460, based on the fuel low heat value parameter, determining the correction amount of the fuel low heat value parameter to the engine geometric compression ratio.

[0154] The step can be refined as: based on the fuel low heat value parameter, multiplying the ratio of the fuel low heat value parameter to a preset fuel low heat value parameter reference value and a geometric compression ratio parameter change amount corresponding to the fuel low heat value parameter to determine a correction amount of the fuel low heat value parameter to the engine geometric compression ratio.

[0155] Specifically, after obtaining the fuel low heat value parameter, the fuel low heat value parameter is divided by the preset fuel low heat value parameter reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change amount corresponding to the fuel low heat value parameter, so that the correction amount of the fuel low heat value parameter to the engine geometric compression ratio can be obtained. The preset fuel low heat value parameter reference value is the fuel low heat value parameter reference value under the current load of the engine, and the obtaining method can directly obtain the preset fuel low heat value parameter reference value from the engine factory. In this embodiment, the preset fuel low heat value parameter reference value can be 50000 kJ / kg. The geometric compression ratio parameter change amount corresponding to the fuel low heat value parameter change amount can be determined according to the fuel low heat value parameter change corresponding relationship specified by the engine factory, or can be determined and corrected through actual experimental conditions.

[0156] S470, based on the gas methane value, determining a correction amount of the gas methane value to the engine geometric compression ratio.

[0157] The step can be refined as: based on the gas methane value, multiplying the ratio of the gas methane value to a preset gas methane value reference value and a geometric compression ratio parameter change amount corresponding to the gas methane value to determine a correction amount of the gas methane value to the engine geometric compression ratio.

[0158] Specifically, after obtaining the gas methane value, the gas methane value is divided by the preset gas methane value reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change amount corresponding to the gas methane value, so that the correction amount of the gas methane value to the engine geometric compression ratio can be obtained. The preset gas methane value reference value is the gas methane value reference value under the current load of the engine, and the obtaining method can directly obtain the preset gas methane value reference value from the engine factory. In this embodiment, the preset gas methane value reference value can be 100. The geometric compression ratio parameter change amount corresponding to the gas methane value change amount can be determined according to the gas methane value parameter change corresponding relationship specified by the engine factory, or can be determined and corrected through actual experimental conditions.

[0159] S480, based on the cylinder explosion pressure change gradient, determining a correction amount of the cylinder explosion pressure change gradient to the engine geometric compression ratio.

[0160] The step can be refined as: based on the cylinder pressure change gradient, multiplying the ratio of the cylinder pressure change gradient to the preset cylinder pressure change gradient reference value by the geometric compression ratio parameter change amount corresponding to the cylinder pressure change gradient to determine the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio.

[0161] Specifically, after obtaining the cylinder pressure change gradient, the cylinder pressure change gradient is divided by the preset cylinder pressure change gradient reference value to obtain the ratio of the two, and the ratio is multiplied by the geometric compression ratio parameter change amount corresponding to the cylinder pressure change gradient, so that the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio can be obtained. The preset cylinder pressure change gradient reference value is the cylinder pressure change gradient reference value under the current load of the engine, and the acquisition mode can acquire the preset cylinder pressure change gradient reference value under the current load according to the load and the running mode. The acquisition mode of the geometric compression ratio parameter change amount corresponding to the cylinder pressure change gradient can be determined according to the cylinder pressure change gradient parameter change corresponding relationship specified when the engine is shipped, or can be determined and corrected through actual experiment.

[0162] S490, determining the target compression ratio of the engine according to the correction amount and the initial geometric compression ratio, and adjusting the engine to the target compression ratio.

[0163] The technical scheme of the embodiment of the application determines the correction amount of the scavenging temperature to the engine geometric compression ratio based on the scavenging temperature, determines the correction amount of the atmospheric pressure to the engine geometric compression ratio based on the atmospheric pressure, determines the correction amount of the supercharger intake temperature to the engine geometric compression ratio based on the supercharger intake temperature, determines the correction amount of the fuel low heat value parameter to the engine geometric compression ratio based on the fuel low heat value parameter, determines the correction amount of the gas methane value to the engine geometric compression ratio based on the gas methane value, and determines the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio based on the cylinder pressure change gradient. By using the above method, the determination of the correction amount in the gas mode is realized, which provides a basis for subsequent determination of the target compression ratio based on the correction amount, and improves the stability of the engine operation.

[0164] Optionally, the cylinder pressure change gradient is dP1, and the preset cylinder pressure change gradient reference value is dP2; before determining the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio by multiplying the ratio of the cylinder pressure change gradient to the preset cylinder pressure change gradient reference value by the geometric compression ratio parameter change amount corresponding to the cylinder pressure change gradient, it further includes: determining that the cylinder pressure change gradient is outside the third preset condition; the third preset condition is 0.8dP2≤dP1≤1.2dP2.

[0165] Specifically, after the cylinder pressure change gradient of the engine is acquired, the cylinder pressure change gradient needs to be first confirmed, and when it is determined that the cylinder pressure change gradient is outside the third preset condition, the correction amount of the engine geometric compression ratio can be determined according to the cylinder pressure change gradient. In the embodiment, the third preset condition is 0.8dP2≤dP1≤1.2dP2, that is, when the cylinder pressure change gradient dP1 is within the above range, the cylinder pressure change gradient is not used as a parameter for compression ratio correction, and only when dP1 is outside the above range, the cylinder pressure change gradient can be used as a parameter for compression ratio correction, and the correction amount of the engine geometric compression ratio corresponding to the cylinder pressure change gradient is determined based on the cylinder pressure change gradient. The reason for such setting is that when the cylinder pressure change gradient is within the above range, it indicates that the current cylinder pressure change gradient is within the normal range, and there is no need to adjust it through engine geometric compression ratio feedback, avoiding unnecessary frequent adjustment and system oscillation.

[0166] Based on the same inventive concept, the embodiment of the present application also provides a marine low-speed engine, which is implemented by using the above-mentioned compression ratio adjusting method for marine low-speed engine, and has the corresponding function modules and beneficial effects of the execution method.

[0167] It should be understood that the various forms of flow shown above can be reordered, added, or deleted steps. For example, each step described in the present application can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, and the present application does not limit this.

[0168] The above specific embodiments do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for adjusting the compression ratio of a marine low-speed engine, characterized in that, include: The initial geometric compression ratio of the engine is determined based on the engine load and the engine operating mode. In the operating mode, the operating parameters of the engine under the current environment are obtained; Based on the operating parameters, determine the correction amount for the engine's geometric compression ratio; Based on the correction amount and the initial geometric compression ratio, the target compression ratio of the engine is determined, and the engine is adjusted to the target compression ratio.

2. The compression ratio adjustment method according to claim 1, characterized in that, After determining the target compression ratio of the engine based on the correction amount and the initial geometric compression ratio, and adjusting the engine to a position prior to the target compression ratio, the method further includes: The target compression ratio is determined to be outside the first preset condition.

3. The compression ratio adjustment method according to claim 2, characterized in that, The target compression ratio is V1, and the initial geometric compression ratio is V2; The first preset condition includes 0.95V2≤V1≤1.05V2, and V1≤V1_min or V1≥V1_max; Wherein, V1_min is the minimum geometric compression ratio of the engine under mechanical constraints, and V1_max is the maximum geometric compression ratio of the engine under mechanical constraints.

4. The compression ratio adjustment method according to claim 1, characterized in that, The engine's operating modes include fuel mode; the operating parameters include scavenging air temperature, atmospheric pressure, turbocharger intake air temperature, fuel quality parameters, and cylinder detonation pressure. Based on the operating parameters, the correction amount for the engine's geometric compression ratio is determined, including: Based on the scavenging air temperature, determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio; Based on the atmospheric pressure, determine the correction amount of the atmospheric pressure to the geometric compression ratio of the engine; Based on the turbocharger intake temperature, determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio; Based on the fuel quality parameters, determine the correction amount of the fuel quality parameters to the engine's geometric compression ratio; Based on the cylinder detonation pressure, the correction amount of the cylinder detonation pressure to the engine's geometric compression ratio is determined.

5. The compression ratio adjustment method according to claim 4, characterized in that, Based on the scavenging air temperature, determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio, including: Based on the scavenging air temperature, the ratio of the scavenging air temperature to a preset scavenging air temperature reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the scavenging air temperature to determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio; and / or, Based on the atmospheric pressure, determine the correction amount of the atmospheric pressure to the engine's geometric compression ratio, including: Based on the atmospheric pressure, the ratio of the atmospheric pressure to a preset atmospheric pressure reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the atmospheric pressure to determine the correction amount of the atmospheric pressure to the engine's geometric compression ratio; and / or, Based on the turbocharger intake temperature, determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio, including: Based on the turbocharger intake temperature, the ratio of the turbocharger intake temperature to a preset turbocharger intake temperature reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the turbocharger intake temperature to determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio; and / or, Based on the fuel quality parameters, determining the correction amount of the fuel quality parameters to the engine's geometric compression ratio includes: Based on the fuel quality parameter, the ratio of the fuel quality parameter to a preset fuel quality parameter reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the fuel quality parameter to determine the correction amount of the fuel quality parameter to the engine's geometric compression ratio; and / or, Based on the cylinder detonation pressure, the correction amount of the cylinder detonation pressure to the engine's geometric compression ratio is determined, including: Based on the cylinder burst pressure, the ratio of the cylinder burst pressure to a preset cylinder burst pressure reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the cylinder burst pressure to determine the correction amount of the cylinder burst pressure to the engine geometric compression ratio.

6. The compression ratio adjustment method according to claim 5, characterized in that, The cylinder burst pressure is P1, and the preset cylinder burst pressure reference value is P2; Before determining the correction amount of the cylinder explosion pressure on the engine's geometric compression ratio based on the cylinder explosion pressure by multiplying the ratio of the cylinder explosion pressure to a preset cylinder explosion pressure reference value by the change in the geometric compression ratio parameter corresponding to the cylinder explosion pressure, the method further includes: It is determined that the cylinder explosion pressure is outside the second preset condition; the second preset condition is P2-3 bar≤P1≤P2+3 bar.

7. The compression ratio adjustment method according to claim 1, characterized in that, The engine's operating mode includes a gas combustion mode; the operating parameters include scavenging air temperature, atmospheric pressure, turbocharger intake air temperature, fuel lower heating value parameter, fuel methane number, and cylinder detonation pressure gradient. Based on the operating parameters, the correction amount for the engine's geometric compression ratio is determined, including: Based on the scavenging air temperature, determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio; Based on the atmospheric pressure, determine the correction amount of the atmospheric pressure to the geometric compression ratio of the engine; Based on the turbocharger intake temperature, determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio; Based on the fuel low heating value parameter, determine the correction amount of the fuel low heating value parameter to the engine geometric compression ratio; Based on the methane number of the fuel gas, determine the correction amount of the methane number of the fuel gas to the geometric compression ratio of the engine; Based on the cylinder detonation pressure change gradient, the correction amount of the cylinder detonation pressure change gradient to the engine geometric compression ratio is determined.

8. The compression ratio adjustment method according to claim 7, characterized in that, Based on the scavenging air temperature, determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio, including: Based on the scavenging air temperature, the ratio of the scavenging air temperature to a preset scavenging air temperature reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the scavenging air temperature to determine the correction amount of the scavenging air temperature to the engine's geometric compression ratio; and / or, Based on the atmospheric pressure, determine the correction amount of the atmospheric pressure to the engine's geometric compression ratio, including: Based on the atmospheric pressure, the ratio of the atmospheric pressure to a preset atmospheric pressure reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the atmospheric pressure to determine the correction amount of the atmospheric pressure to the engine's geometric compression ratio; and / or, Based on the turbocharger intake temperature, determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio, including: Based on the turbocharger intake temperature, the ratio of the turbocharger intake temperature to a preset turbocharger intake temperature reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the turbocharger intake temperature to determine the correction amount of the turbocharger intake temperature to the engine's geometric compression ratio; and / or, Based on the fuel's lower heating value parameter, determine the correction amount of the fuel's lower heating value parameter to the engine's geometric compression ratio, including: Based on the fuel's low calorific value parameter, the ratio of the fuel's low calorific value parameter to a preset fuel low calorific value parameter reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the fuel's low calorific value parameter to determine the correction amount of the fuel's low calorific value parameter to the engine's geometric compression ratio; and / or, Based on the methane number of the fuel gas, determine the correction amount of the methane number of the fuel gas to the geometric compression ratio of the engine, including: Based on the methane value of the fuel gas, the ratio of the methane value of the fuel gas to a preset reference value of the methane value of the fuel gas is multiplied by the change in the geometric compression ratio parameter corresponding to the methane value of the fuel gas to determine the correction amount of the methane value of the fuel gas to the geometric compression ratio of the engine; and / or, Based on the cylinder detonation pressure change gradient, determine the correction amount of the cylinder detonation pressure change gradient to the engine's geometric compression ratio, including: Based on the cylinder detonation pressure change gradient, the ratio of the cylinder detonation pressure change gradient to a preset cylinder detonation pressure change gradient reference value is multiplied by the change in the geometric compression ratio parameter corresponding to the cylinder detonation pressure change gradient to determine the correction amount of the cylinder detonation pressure change gradient to the engine geometric compression ratio.

9. The compression ratio adjustment method according to claim 8, characterized in that, The cylinder explosion pressure change gradient is dP1, and the preset cylinder explosion pressure change gradient reference value is dP2; Before determining the correction amount of the cylinder pressure change gradient to the engine geometric compression ratio based on the cylinder pressure change gradient by multiplying the ratio of the cylinder pressure change gradient to a preset cylinder pressure change gradient reference value with the change in the geometric compression ratio parameter corresponding to the cylinder pressure change gradient, the method further includes: The cylinder explosion pressure change gradient is determined to be outside the third preset condition; the third preset condition is 0.8dP2≤dP1≤1.2dP2.

10. The compression ratio adjustment method according to claim 1, characterized in that, Determining the target compression ratio of the engine based on the correction amount and the initial geometric compression ratio includes: Based on the correction amount and the initial geometric compression ratio, the target compression ratio of the engine is determined according to the first calculation formula; The first calculation formula is: V1=V2×(1+V3), where V1 is the target compression ratio, V2 is the initial geometric compression ratio, and V3 is the correction amount.

11. A marine low-speed engine, characterized in that, The compression ratio adjustment method for marine low-speed engines as described in any one of claims 1-10 is adopted.

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