Control method and device of methanol-gasoline flexible fuel engine and storage medium

Abstract

The invention relates to a control method and device for a methanol-gasoline flexible fuel engine and a storage medium. The method comprises the steps that when the engine is started, the engine is controlled to operate according to a working mode corresponding to the historical methanol content recorded before the last shutdown of the engine; in the running process of the engine, the current excess air coefficient collected by the front oxygen sensor is obtained and used for determining the target methanol content; and the engine is controlled to operate according to the working mode corresponding to the target methanol content, then the fuel injection quantity of the fuel injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor, and closed-loop control over the excess air coefficient is achieved. By adopting the technical scheme, the dependence of monitoring fuel components on a flexible fuel sensor and the high cost caused by adopting the flexible fuel sensor are avoided, so that the problems of poor dynamic property, economical efficiency reduction and emission deterioration of the whole vehicle caused by poor measurement precision of the flexible fuel sensor are avoided, the methanol content is quickly and accurately obtained, and the reliability of the whole vehicle is improved. Therefore, the low-emission effect is achieved.

Description

Technical Field

[0001] The present disclosure relates to the field of engine control technology, and in particular to a control method, device and storage medium for a methanol-gasoline flexible fuel engine. Background Art

[0002] At present, most methanol engines on the market are fuel intake port injection control systems. In order to solve the problem of low-temperature cold start difficulties, they are usually equipped with two main and auxiliary fuel tanks. When the methanol fuel content is greater than 10% monitored by the flexible fuel sensor, the auxiliary fuel tank (gasoline) is used to achieve low-temperature cold start; or, high-pressure fuel direct injection, high compression ratio, and high-energy ignition coil technology are used to achieve low-temperature cold start of the engine under different methanol contents. After the cold start is completed, the methanol content in the fuel is monitored by the flexible fuel sensor, and the measured data is transmitted to the engine controller. The engine controller calls the corresponding working mode according to the methanol content to adjust the control parameters, so that the engine burns at an equivalent ratio under the corresponding methanol concentration to achieve the minimum emission requirements.

[0003] However, the use of flexible fuel sensors to monitor the methanol content in the fuel has the problem of poor fuel composition measurement accuracy, which leads to problems such as poor vehicle power, reduced economy, and worsening emissions. Summary of the invention

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, at least one embodiment of the present disclosure provides a control method, device and storage medium for a methanol-gasoline flexible fuel engine.

[0005] In a first aspect, the present disclosure provides a control method for a methanol-gasoline flexible fuel engine, comprising:

[0006] In response to monitoring that the engine is started, controlling the engine to operate according to an operating mode corresponding to a historical methanol content recorded before the engine was most recently shut down;

[0007] During the operation of the engine, obtaining a current excess air coefficient collected by a front oxygen sensor;

[0008] Determining a target methanol content according to a difference between the current excess air coefficient and a standard excess air coefficient;

[0009] Controlling the engine to operate in a working mode corresponding to the target methanol content;

[0010] After the engine is operated in the working mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

[0011] In a second aspect, the present disclosure provides a control device for a methanol-gasoline flexible fuel engine, comprising:

[0012] A control module, configured to, in response to detecting engine startup, control the engine to operate in accordance with an operating mode corresponding to a historical methanol content recorded before the engine was most recently shut down;

[0013] A coefficient acquisition module, used for acquiring a current excess air coefficient collected by a front oxygen sensor during the operation of the engine;

[0014] A content determination module, used to determine a target methanol content according to a difference between the current excess air coefficient and a standard excess air coefficient;

[0015] The control module is further used to control the engine to operate in a working mode corresponding to the target methanol content;

[0016] The adjustment module is used to adjust the fuel injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor after the engine operates in the working mode corresponding to the target methanol content, so as to realize closed-loop control of the excess air coefficient.

[0017] In a third aspect, the present disclosure provides an electronic device, including: a processor and a memory;

[0018] The processor is used to execute the control method of the methanol-gasoline flexible fuel engine as described in the first aspect by calling the program or instruction stored in the memory.

[0019] In a fourth aspect, the present disclosure provides a computer-readable storage medium storing a program or instruction, wherein the program or instruction enables a computer to execute the control method of the methanol-gasoline flexible fuel engine as described in the first aspect.

[0020] In a fifth aspect, the present disclosure provides a computer program product, wherein the computer program product is used to execute the control method of the methanol-gasoline flexible fuel engine as described in the first aspect.

[0021] In a sixth aspect, the present disclosure provides a vehicle comprising a control device for a methanol-gasoline flexible fuel engine as described in the second aspect, or an electronic device as described in the third aspect, or a computer-readable storage medium as described in the fourth aspect, or a computer program product as described in the fifth aspect.

[0022] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has at least the following advantages:

[0023] In the disclosed embodiment, in response to monitoring the engine start, the engine is controlled to operate in an operating mode corresponding to the historical methanol content recorded before the engine was most recently shut down, and during the engine operation, the current excess air coefficient collected by the front oxygen sensor is obtained, and the target methanol content is determined based on the difference between the current excess air coefficient and the standard excess air coefficient, and then the engine is controlled to operate in an operating mode corresponding to the target methanol content. After the engine operates in the operating mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor, so as to realize closed-loop control of the excess air coefficient. By adopting the above technical scheme, the current excess air coefficient is collected by the front oxygen sensor, and the target methanol content is determined according to the difference between the current excess air coefficient and the standard excess air coefficient, so as to replace the flexible fuel sensor to monitor the methanol content in the fuel, thereby avoiding the dependence on flexible fuel sensors for monitoring the fuel composition and the high cost of using flexible fuel sensors, thereby avoiding the poor power performance, reduced economy and worsening emissions of the whole vehicle caused by the poor measurement accuracy of flexible fuel sensors. By first controlling the working mode of the engine according to the determined target methanol content, and then adjusting the injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor, the methanol content can be quickly and accurately obtained, and a fast closed loop of excess air coefficient control can be achieved, thereby achieving a low emission effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0026] Figure 1 A flow chart of a control method for a methanol-gasoline flexible fuel engine provided by an exemplary embodiment of the present disclosure;

[0027] Figure 2 A schematic diagram of the system structure of a control method for a methanol-gasoline flexible fuel engine of the present disclosure is shown in accordance with an exemplary embodiment of the present disclosure;

[0028] Figure 3 A flow chart of a control method for a methanol-gasoline flexible fuel engine provided by another exemplary embodiment of the present disclosure;

[0029] FIG4( a ) shows a schematic diagram of the excess air coefficient corresponding to each methanol content in the working mode with a methanol content of 0%;

[0030] FIG4( b ) shows a schematic diagram of the excess air coefficient corresponding to each methanol content in the working mode with a methanol content of 45%;

[0031] FIG4( c ) shows a schematic diagram of the excess air coefficient corresponding to each methanol content in the working mode with a methanol content of 100%;

[0032] Figure 5 A schematic diagram showing the relationship between air-fuel ratio and vehicle speed under a deceleration fuel cut-off condition of an exemplary embodiment of the present disclosure is shown;

[0033] Figure 6 A schematic diagram showing the relationship between catalyst conversion rate and theoretical air-fuel ratio of an exemplary embodiment of the present disclosure is shown;

[0034] Figure 7 A schematic diagram of the structure of a control device for a methanol-gasoline flexible fuel engine provided in one embodiment of the present disclosure. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned purposes, features and advantages of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and embodiments. It is understandable that the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments, and the specific embodiments described herein are only used to explain the present disclosure, rather than to limit the present disclosure. In the absence of conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in the field belong to the scope of protection of the present disclosure.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0037] At present, most methanol engines on the market are fuel intake port injection control systems. In order to solve the problem of low-temperature cold start difficulties, the technical routes adopted can be roughly divided into the following two types:

[0038] (1) With flexible fuel sensor and no auxiliary fuel tank: The fuel cylinder direct injection mode solves the low-temperature cold start problem and relies on flexible fuel sensors to monitor the methanol content of the fuel, which is costly and cannot guarantee long-term stability;

[0039] (2) No flexible fuel sensor, but with auxiliary fuel tank: The methanol content in the fuel is determined based on algorithm estimation and comparison. This has problems such as high emissions, imprecise control, and high cost, and is relatively complex.

[0040] However, the existing method of monitoring the methanol content in the fuel through a flexible fuel sensor has the disadvantages of poor fuel composition measurement accuracy (especially when there are impurities in the fuel), immature sensor design and manufacturing, and high cost. The inaccurate measurement of methanol content by the flexible fuel sensor can easily lead to problems such as poor vehicle power, reduced economy, and worsened emissions. Based on this, the present disclosure provides a control scheme for a methanol-gasoline flexible fuel engine that does not rely on a flexible fuel sensor. It does not rely on a flexible fuel sensor, eliminates the auxiliary fuel tank, and has a relatively simple vehicle structure and reduced costs. This scheme uses a front oxygen sensor to close the loop to measure the methanol content in a methanol-gasoline mixed fuel mixed in any proportion, which can achieve rapid and accurate measurement of any methanol content, low emissions, and low costs. In addition, this scheme also proposes optimization measures for the stratification problem of methanol-gasoline flexible fuel (methanol-gasoline mixed fuel), so that the engine control is more accurate and the emissions are lower, and the problems of poor engine power and reduced economy in the stratification transition area, slow response to equivalent ratio combustion control, and high emissions when stratification occurs in methanol-gasoline flexible fuel are solved.

[0041] The specific implementation methods of the control method, device and storage medium of the methanol-gasoline flexible fuel engine disclosed in the present invention are explained in detail below with reference to the accompanying drawings.

[0042] Figure 1 A flow chart of a method for controlling a methanol-gasoline flexible-fuel engine provided in accordance with an exemplary embodiment of the present disclosure is provided. The method may be executed by a control device for a methanol-gasoline flexible-fuel engine provided in accordance with an exemplary embodiment of the present disclosure. The control device for a methanol-gasoline flexible-fuel engine may be implemented using software and / or hardware and may be integrated into a vehicle, specifically an engine controller of the vehicle, which may be an electronic control unit (ECU).

[0043] For example, Figure 2 A schematic diagram of the system structure of a control method for a methanol-gasoline flexible fuel engine according to an exemplary embodiment of the present disclosure is shown. Figure 2As shown, the system includes an engine controller, a high-precision linear wide-range front oxygen sensor, an intake pressure temperature sensor, a high-pressure fuel pump, a fuel rail injector assembly, a low-pressure fuel tank, a fuel heater, a fuel temperature sensor, an electronic throttle body, a crankshaft position sensor, a high-energy ignition coil, a coolant temperature sensor, a high-pressure fuel pressure sensor, a spark plug and other components. The engine controller determines the target methanol content by executing the scheme disclosed in the present invention, and adjusts the parameters of each component in the engine according to the working mode corresponding to the target methanol content, so that the engine operates according to the working mode corresponding to the target methanol content.

[0044] like Figure 1 As shown, the control method of the methanol-gasoline flexible fuel engine may include the following steps:

[0045] Step 101, in response to monitoring that the engine is started, controlling the engine to operate according to an operating mode corresponding to a historical methanol content recorded before the engine was most recently shut down.

[0046] In this embodiment, before each engine shutdown, the current methanol content is recorded, and when the engine is started next time, the operating mode corresponding to the historical methanol content is determined based on the most recently recorded methanol content (for ease of description and distinction, referred to as the historical methanol content), and the engine operation is controlled according to the operating mode, that is, the operating parameters of various engine components are adjusted according to the operating mode.

[0047] The working modes corresponding to different methanol contents can be determined in advance by testing and stored in the engine controller so as to be queried and called when needed. Specifically, a methanol-gasoline flexible fuel with a determined methanol content can be used to measure the operating parameters of various engine components when the mixed fuel is burned at an equivalent ratio (excess air coefficient λ=1) as the working mode corresponding to the methanol content of the mixed fuel, thereby obtaining the working mode corresponding to each methanol content and writing it into the engine controller. Exemplarily, the methanol content of methanol-gasoline flexible fuel can be divided into 21 types, namely, M0, M5, M10, M15, M20, M25, M30, M35, M40, M45, M50, M55, M60, M65, M70, M75, M80, M85, M90, M95 and M100, wherein n (n is 0, 5, 10 ... 95, 100) in Mn represents the methanol content, i.e., the percentage of methanol in the methanol-gasoline flexible fuel, thereby determining 21 corresponding working modes, and the working mode division is shown in the following Table 1. It should be noted that the above 21 types of methanol content division are only used as examples to explain the present disclosure, and cannot be used as a limitation of the present disclosure. The division of methanol content and working mode can also be increased as needed, and the finer the division, the more accurate the engine control.

[0048] Table 1

[0049]

[0050] As can be seen from Table 1, the working mode corresponding to the methanol content M0 can be recorded as the M0 working mode, and the working mode corresponding to the methanol content M95 can be recorded as the M95 working mode. Each working mode includes parameters such as intake pressure, intake temperature, injection pulse width, engine speed, power, throttle opening, coolant temperature, high-pressure fuel pressure, and ignition advance angle.

[0051] In this embodiment, when the engine is monitored to be started, the historical methanol content recorded when the engine was last shut down can be obtained, and the above Table 1 can be queried based on the historical methanol content to determine the corresponding working mode, and then the engine can be controlled according to the parameters of each part under the working mode.

[0052] It should be noted that, in this embodiment, the methanol content and the corresponding operating mode shown in Table 1 are only used as examples to explain the present disclosure, and cannot be used as a limitation of the present disclosure. The parameters included in the operating mode can also be increased or decreased as needed to make the engine control more precise.

[0053] Step 102: During the operation of the engine, obtain the current excess air coefficient collected by the front oxygen sensor.

[0054] The front oxygen sensor may be, for example, a high-precision linear wide-range front oxygen sensor.

[0055] In this embodiment, after the engine is started, it enters a stable operation stage. During the operation of the engine, the front oxygen sensor can collect the current excess air coefficient in real time or periodically, and feed the collected current excess air coefficient back to the engine controller.

[0056] Step 103, determining the target methanol content according to the difference between the current excess air coefficient and the standard excess air coefficient.

[0057] The standard excess air coefficient is a theoretical value, for example, the standard excess air coefficient can be set to 1.

[0058] In this embodiment, after the engine controller obtains the current excess air coefficient collected by the front oxygen sensor, it can calculate the difference between the current excess air coefficient and the standard excess air coefficient, and determine the target methanol content based on the difference.

[0059] For example, if the difference between the current excess air coefficient and the standard excess air coefficient is greater than a preset value, or the difference between the standard excess air coefficient and the current excess air coefficient is greater than a preset value, the methanol content corresponding to the current excess air coefficient is determined to be the target methanol content.

[0060] Step 104, controlling the engine to operate in a working mode corresponding to the target methanol content.

[0061] In this embodiment, after the target methanol content is determined, the operating mode corresponding to the target methanol content can be determined according to the operating modes corresponding to different methanol contents, and the engine can be controlled to operate according to the operating mode corresponding to the target methanol content.

[0062] It should be noted that, in this embodiment, if the difference between the current excess air coefficient and the standard excess air coefficient is small, the engine continues to operate according to the working mode corresponding to the historical methanol content, thereby realizing closed-loop adjustment of the working mode.

[0063] Step 105, after the engine is running in the working mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

[0064] In this embodiment, the front oxygen sensor continuously feeds back the excess air coefficient. After the engine is operated in the working mode corresponding to the target methanol content, the excess air coefficient collected by the front oxygen sensor is continuously obtained, and the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor, so as to realize the closed-loop control of the excess air coefficient. Specifically, if the excess air coefficient currently fed back by the front oxygen sensor is greater than 1, it is determined that the exhaust gas is too lean at this time, so as to increase the injection pulse width of the injector to increase the injection amount; if the excess air coefficient currently fed back by the front oxygen sensor is less than 1, it is determined that the exhaust gas is too rich at this time, so as to reduce the injection pulse width of the injector to reduce the injection amount, so as to quickly adjust the excess air coefficient to the range of 0.98 to 1.02, quickly realize the closed loop of the excess air coefficient, and achieve the low emission target.

[0065] It should be noted that in the present embodiment, the engine controller continuously obtains the current excess air coefficient collected by the front oxygen sensor during operation, and determines the target methanol content according to the difference between the current excess air coefficient and the standard excess air coefficient, and then controls the engine operation according to the corresponding working mode. After the engine operates in the working mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor, thereby achieving timely and accurate adjustment of the engine's working mode during engine operation and realizing rapid closed loop of the excess air coefficient, thereby achieving low emissions.

[0066] The control method of the methanol-gasoline flexible fuel engine of the disclosed embodiment controls the engine to operate in an operating mode corresponding to the historical methanol content recorded before the engine was most recently shut down in response to monitoring the engine start-up, and during the engine operation, obtains the current excess air coefficient collected by the front oxygen sensor, determines the target methanol content according to the difference between the current excess air coefficient and the standard excess air coefficient, and then controls the engine to operate in the operating mode corresponding to the target methanol content. After the engine operates in the operating mode corresponding to the target methanol content, adjusts the fuel injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor, so as to realize closed-loop control of the excess air coefficient. By adopting the above technical scheme, the current excess air coefficient is collected by the front oxygen sensor, and the target methanol content is determined according to the difference between the current excess air coefficient and the standard excess air coefficient, so as to replace the flexible fuel sensor to monitor the methanol content in the fuel, thereby avoiding the dependence on the flexible fuel sensor for monitoring the fuel composition and the high cost of using the flexible fuel sensor, thereby avoiding the poor power performance, reduced economy and worsening emissions of the whole vehicle caused by the poor measurement accuracy of the flexible fuel sensor, and realizing the rapid and accurate acquisition of the methanol content. By first controlling the working mode of the engine according to the determined target methanol content, and then adjusting the injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor, the methanol content is quickly and accurately acquired, and a rapid closed loop of the excess air coefficient control is realized, thereby achieving a low emission effect.

[0067] In an optional embodiment of the present disclosure, Figure 3 As shown, based on the above embodiment, step 103 may include the following sub-steps:

[0068] Step 201, calculating the absolute value of the difference between the current excess air coefficient and the standard excess air coefficient.

[0069] In this embodiment, after the current excess air coefficient collected by the front oxygen sensor is obtained, the absolute value of the difference between the current excess air coefficient and the standard excess air coefficient may be calculated.

[0070] Step 202, when the absolute value is greater than the first threshold, obtain a correspondence table between historical methanol content and excess air coefficient, wherein the correspondence table between historical methanol content and excess air coefficient records the correspondence between different methanol contents and excess air coefficients under the working mode corresponding to the historical methanol content.

[0071] The first threshold may be set according to actual needs, for example, the first threshold may be set to 0.01.

[0072] In this embodiment, the absolute value of the difference between the current excess air coefficient and the standard excess air coefficient calculated can be compared with the first threshold value, and if the obtained absolute value is greater than the first threshold value, a correspondence table between historical methanol content and excess air coefficient is obtained. It should be noted that the correspondence table is only a form of representation of the correspondence between recorded data, and the correspondence between data can also be recorded in other forms, such as a curve chart, and the present disclosure does not limit this.

[0073] Exemplarily, the parameters of various engine components can be adjusted in advance for each methanol content according to the operating mode corresponding to the methanol content, and methanol-gasoline flexible fuels of each methanol content other than the methanol content can be used for testing. The excess air coefficient collected by the front oxygen sensor when using each other methanol content is measured and recorded to form a correspondence table between each methanol content and the excess air coefficient under the operating mode of the current methanol content, and the obtained correspondence table is stored in the engine controller for query and call when needed, wherein, under the operating mode of the current methanol content, the excess air coefficient of the current methanol content is 1.

[0074] For example, assuming that the methanol content in methanol-gasoline flexible fuel is divided into 21 types, namely M0, M5, M10, M15, M20, M25, M30, M35, M40, M45, M50, M55, M60, M65, M70, M75, M80, M85, M90, M95 and M100, corresponding to 21 working modes, the parameters of various engine components are adjusted in turn according to each working mode, and the excess air coefficient collected by the front oxygen sensor when using methanol-gasoline flexible fuel with the remaining 20 methanol capacities is measured to form a correspondence table between each methanol content and the excess air coefficient. The correspondence table records the excess air coefficients corresponding to the 21 methanol contents under the methanol content working mode, where the excess air coefficient corresponding to the methanol content is 1. Exemplarily, Figure 4(a) shows a schematic diagram of the excess air coefficient corresponding to each methanol content under the working mode with a methanol content of 0% (M0), Figure 4(b) shows a schematic diagram of the excess air coefficient corresponding to each methanol content under the working mode with a methanol content of 45% (M45), and Figure 4(c) shows a schematic diagram of the excess air coefficient corresponding to each methanol content under the working mode with a methanol content of 100% (M100).

[0075] In this embodiment, since the engine is started in accordance with the working mode corresponding to the historical methanol content, when the calculated absolute value is greater than the first threshold, the corresponding relationship table of the historical methanol content and the excess air coefficient can be obtained. For example, assuming that the historical methanol content is 45%, the corresponding relationship between each methanol content and the excess air coefficient shown in Figure 4 (b) is obtained.

[0076] Step 203, querying the correspondence table between historical methanol content and excess air coefficient, and determining the methanol content corresponding to the excess air coefficient with the smallest difference from the current excess air coefficient as the target methanol content.

[0077] In this embodiment, after obtaining the correspondence table between historical methanol content and excess air coefficient, the correspondence table between historical methanol content and excess air coefficient can be queried to determine the methanol content corresponding to the excess air coefficient with the smallest difference (i.e., closest) to the current excess air coefficient as the target methanol content.

[0078] For example, assuming that the historical methanol content is 45%, the corresponding relationship table is obtained as shown in Figure 4(b), and the current excess air coefficient is 0.96. By querying Figure 4(b), it can be determined that the methanol content corresponding to the excess air coefficient closest to the current excess air coefficient is 30% (M30, the corresponding excess air coefficient is 0.95), that is, the target methanol content is determined to be M30.

[0079] Step 204: when the absolute value is not greater than the first threshold, determine the historical methanol content as the target methanol content.

[0080] In this embodiment, if the absolute value of the calculated difference between the current excess air coefficient and the standard excess air coefficient is not greater than the first threshold, the historical methanol content is determined as the target methanol content, and the operating parameters of the engine will not change.

[0081] The control method of the methanol-gasoline flexible fuel engine of the present embodiment calculates the absolute value of the difference between the current excess air coefficient and the standard excess air coefficient, and when the absolute value is greater than a first threshold value, obtains a correspondence table between historical methanol content and excess air coefficient, wherein the correspondence table between historical methanol content and excess air coefficient records the correspondence between different methanol contents and excess air coefficients under the working mode corresponding to the historical methanol content, and queries the correspondence table between historical methanol content and excess air coefficient to determine that the methanol content corresponding to the excess air coefficient with the smallest difference from the current excess air coefficient is the target methanol content, and when the absolute value is not greater than the first threshold value, determines the historical methanol content as the target methanol content, thereby being able to accurately determine the current methanol content, so that the engine operates in the working mode of the current methanol content, thereby realizing closed-loop regulation of the engine working mode.

[0082] Further, in an optional embodiment of the present disclosure, after adjusting the injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor and completing the closed-loop control of the excess air coefficient, the target methanol content can be recorded to control the engine to operate in the working mode corresponding to the target methanol content when the engine is started next time. For example, each time the current target methanol content is recorded, the target methanol content to be recorded this time can be used to overwrite the methanol content recorded last time to ensure that the stored methanol content is the latest, thereby ensuring the rationality and accuracy of the engine operating in the working mode corresponding to the recorded methanol content when it is started next time.

[0083] When the engine is operating in a deceleration and fuel cut-off condition, too much air (oxygen) will be introduced into the exhaust system, causing the excess air coefficient fed back by the front oxygen sensor to be abnormally large, so that the collected excess air coefficient is no longer accurate, and the air-fuel ratio also changes dramatically, such as Figure 5 As shown, in this case, the engine operating parameters can no longer be adjusted by relying on the excess air coefficient. Therefore, in this embodiment, the engine methanol content working mode is not switched or corrected under the deceleration fuel cut-off condition, and the methanol content determined under the engine deceleration fuel cut-off condition is not recorded. It should be noted that the engine deceleration fuel cut-off condition here refers to the deceleration fuel cut-off generated after the working mode adjustment and the excess air coefficient closed-loop control are completed, and before the working mode is determined and the excess air coefficient enters the closed-loop control, the engine cannot have a deceleration fuel cut-off condition.

[0084] In an optional embodiment of the present disclosure, before the engine is started, or before the engine is controlled to operate in an operating mode corresponding to the target methanol content, it is also possible to first determine whether a fueling status signal is obtained before the engine is started. When it is determined that a fueling status signal is obtained, the engine is controlled to operate in an operating mode corresponding to the target methanol content.

[0085] Among them, the body controller can determine whether the vehicle is refueling by identifying the fuel tank cap opening signal, fuel tank liquid level changes, etc. When it is determined that the vehicle is refueling, the body controller sends a refueling status signal to the engine controller to inform the engine controller that the vehicle is refueling. When the engine controller receives the refueling status signal, it can be determined that the vehicle has undergone a refueling operation.

[0086] In this embodiment, it is first determined whether a fueling status signal is obtained before the engine is started, that is, it is determined whether this engine start is the first start after the refueling (gasoline or methanol) operation. If it is (that is, the refueling status signal is obtained before the engine is started), then after the target methanol content is determined, the engine is controlled to operate in the working mode corresponding to the target methanol content.

[0087] It is understandable that when the refueling operation occurs, the methanol-gasoline content changes, and a methanol-gasoline flexible fuel with any methanol content (0≤Mx≤100) is formed. When the engine is started, it operates in the working mode corresponding to the methanol content determined before refueling (i.e., the historical methanol content). The methanol content before refueling is recorded as M before , monitor and read the excess air coefficient collected by the stable front oxygen sensor at the specified operating point, recorded as λ x :①If |λ x -1|>First threshold, in M before -λ relationship (i.e. M before Find λ in the corresponding relationship with the excess air coefficient x The closest λ value is determined, so that the methanol content corresponding to the λ is the methanol content after refueling, which is recorded as M after , the engine is based on M after The working mode corresponding to the methanol content is operated; ② If |λ x -1|≤ the first threshold, indicating that the methanol content of the mixed fuel after refueling is before If the M before The operating mode corresponding to the methanol content continues to operate. after After the working mode corresponding to the methanol content is running, it is necessary to continue to monitor the excess air coefficient fed back by the front oxygen sensor, which is recorded as λ f ①If |λ f -1|>First threshold, in M after -λ relationship (i.e. M after Find λ in the corresponding relationship with the excess air coefficient f The closest λ value is used to determine the methanol content corresponding to this λ, which is recorded as M fix , according to M fix The corresponding working mode corrects the operating parameters of the engine; ② If |λ f -1|≤ the first threshold, the engine still follows M after The working mode corresponding to the methanol content continues to operate.

[0088] Within a certain temperature range, the mutual solubility of methanol-gasoline flexible fuel with the same methanol content increases with increasing temperature. Therefore, increasing the temperature can reduce the probability of stratification of methanol-gasoline flexible fuel. Methanol-gasoline flexible fuel is very prone to stratification in the temperature range of -35℃ to -15℃. When the temperature is above 28℃, methanol and gasoline can be miscible in any proportion. Based on this, the present disclosure proposes a scheme for designing a fuel tank with a controllable fuel heater and a fuel temperature sensor. The fuel temperature sensor is used to monitor the temperature of the methanol-gasoline flexible fuel in the fuel tank, and the fuel heater is used to heat the fuel tank when the temperature collected by the fuel temperature sensor is lower than the temperature threshold. The fuel temperature is fed back in real time by the fuel temperature sensor. When the fuel temperature is lower than 28℃ (different temperature limits can also be set according to the methanol content), the fuel heater is started to heat the methanol-gasoline flexible fuel, and the fuel temperature is closed-loop controlled to suppress the stratification of methanol gasoline in a low temperature environment. Therefore, in an optional embodiment of the present disclosure, the method of the present disclosure also includes: obtaining the current temperature collected by the fuel temperature sensor, and when the current temperature is lower than the temperature threshold, starting the fuel heater to heat the fuel tank to heat the methanol-gasoline flexible fuel in the fuel tank to prevent methanol gasoline stratification. The temperature threshold can be set according to the requirements, for example, the temperature threshold can be set to 28°C.

[0089] Furthermore, in an optional embodiment of the present disclosure, when it is determined that the refueling status signal is not obtained and the temperature collected by the fuel temperature sensor is lower than the target temperature, that is, the vehicle has not performed a refueling operation before the engine is started, and the temperature is lower than the target temperature so that the methanol gasoline is stratified, wherein the target temperature is the highest temperature of the methanol gasoline stratification, usually -10°C, then the absolute value of the content difference between the target methanol content and the historical methanol content is further calculated, that is, |target methanol content-historical methanol content|, and when the absolute value of the content difference is greater than the stratification threshold, it is further determined whether the target methanol content is within a preset methanol content range, the methanol content range includes a lower limit value of the methanol content and an upper limit value of the methanol content, and the methanol content range can be recorded as [lower limit value of the methanol content, upper limit value of the methanol content]. When the target methanol content is greater than the upper limit of the methanol content, the engine is controlled to operate in the working mode corresponding to 100% methanol content, and after the engine operates in the working mode corresponding to 100% methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient; when the target methanol content is less than the lower limit of the methanol content, the engine is controlled to operate in the working mode corresponding to 0% methanol content, and after the engine operates in the working mode corresponding to 0% methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient; when the absolute value of the content difference is not greater than the stratification threshold, or the target methanol content is within the methanol content range, the engine is controlled to operate in the working mode corresponding to the target methanol content, and after the engine operates in the working mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

[0090] Among them, the stratification threshold, the lower limit of methanol content and the upper limit of methanol content can all be set according to actual needs. For example, the stratification threshold can be set to 20, the lower limit of methanol content can be set to 10, and the upper limit of methanol content can be set to 90.

[0091] Under the premise that no refueling operation occurs, when methanol-gasoline flexible fuel stratification occurs, the engine control strategy can be executed in different situations:

[0092] (1) Tank bottom area: After the methanol-gasoline flexible fuel stratification occurs, the fuel M100 with a methanol content close to 100% is formed at the bottom of the tank. after -M before > stratification threshold and methanol content M after>M90, in order to quickly enter equivalence ratio combustion, the engine operating mode is directly switched to the operating mode corresponding to the methanol content of M100 for engine control; after Refers to the determined target methanol content, M before Refers to historical methanol content;

[0093] (2) Upper layer of the fuel tank: After the methanol-gasoline flexible fuel stratification occurs, a fuel M0 (methanol content is 0%) close to pure gasoline is formed in the upper layer of the fuel tank. before -M after > stratification threshold and methanol content M after When the engine temperature is less than M10, in order to quickly enter the equivalent ratio combustion, the engine operating mode is directly switched to the operating mode corresponding to the M0 methanol content for engine control;

[0094] (3) Stratified transition region: In the stratified transition region, the methanol content entering the combustion chamber is extremely unstable. after -M before | may not be greater than the stratification threshold, or, M10≤M after ≤M90, in this case, the engine is controlled to operate in an operating mode corresponding to the target methanol content to achieve closed-loop control, so that the engine burns at an equivalent ratio, wherein the target methanol content is determined based on the difference between the current excess air coefficient and the standard excess air coefficient. For details, please refer to the relevant description of the aforementioned embodiment, which will not be repeated here).

[0095] In the disclosed embodiment, it is first determined whether a fueling status signal is obtained before the engine is started. If the fueling status signal is obtained, the engine is controlled to operate in an operating mode corresponding to the target methanol content. If the fueling status signal is not obtained, it is further determined whether the absolute value of the difference between the target methanol content and the historical methanol content is greater than the stratification threshold, and when the absolute value is greater than the stratification threshold and the target methanol content is less than the lower limit of the methanol content, the engine is controlled to operate in an operating mode corresponding to 0% methanol content; when the absolute value is greater than the stratification threshold and the target methanol content is greater than the upper limit of the methanol content, the engine is controlled to operate in an operating mode corresponding to 100% methanol content. In this way, rapid correction of the engine operating mode can be achieved, thereby improving control efficiency.

[0096] In an optional embodiment of the present disclosure, the scheme of the present disclosure also includes controlling the engine start based on the injection correction factor corresponding to the historical methanol content when the engine is started, and obtaining the excess air coefficient collected by the oxygen sensor during the engine start process; when the excess air coefficient is less than the second threshold, reducing the injection correction factor according to the first step; when the excess air coefficient is greater than the third threshold, increasing the injection correction factor according to the second step.

[0097] Among them, the second threshold, the third threshold, the first step length and the second step length can all be set according to actual needs.

[0098] It can be understood that when the excess air coefficient is too large, it indicates that there is too much oxygen and the air-fuel ratio is too lean. At this time, the injection correction factor needs to be increased to increase the injection amount; when the excess air coefficient is too small, it indicates that there is too little oxygen and the air-fuel ratio is too rich. At this time, the injection correction factor needs to be reduced to reduce the injection amount.

[0099] That is to say, in this embodiment, when the engine is started when it is cold or hot, it runs according to the working mode corresponding to the methanol content before shutdown recorded by the engine controller, and the injection correction factor corresponding to the methanol content before shutdown is used to control the engine start. As the engine coolant temperature increases, the injection correction factor gradually decreases, so that the air-fuel ratio gradually approaches the target air-fuel ratio, achieving equivalent ratio combustion, and the engine methanol content working mode is not switched or corrected during the startup process.

[0100] The switching of working modes with different methanol contents and the rapid response of the program after methanol gasoline stratification are all to achieve engine equivalent ratio combustion in the shortest time. Studies have shown that when the actual air-fuel ratio is between 0.98 and 1.02 (including 0.98 and 1.02), the catalyst conversion rate is the highest and the comprehensive exhaust emissions are the lowest. Among them, the relationship between catalyst conversion rate and theoretical air-fuel ratio is as follows Figure 6 shown.

[0101] In order to implement the above embodiments, the present disclosure also provides a control device for a methanol-gasoline flexible fuel engine. The control device for a methanol-gasoline flexible fuel engine can be implemented using software and / or hardware and can be integrated into a vehicle, specifically, can be integrated into an engine controller of the vehicle.

[0102] Figure 7 A schematic diagram of the structure of a control device for a methanol-gasoline flexible fuel engine provided by an embodiment of the present disclosure, such as Figure 7 As shown, the control device 30 of the methanol-gasoline flexible fuel engine may include: a control module 310 , a coefficient acquisition module 320 , a content determination module 330 and an adjustment module 340 .

[0103] The control module 310 is used to control the engine to operate according to the operating mode corresponding to the historical methanol content recorded before the engine was most recently shut down in response to monitoring the engine starting;

[0104] The coefficient acquisition module 320 is used to acquire the current excess air coefficient collected by the front oxygen sensor during the operation of the engine;

[0105] The content determination module 330 is used to determine the target methanol content according to the difference between the current excess air coefficient and the standard excess air coefficient;

[0106] The control module 310 is further used to control the engine to operate in a working mode corresponding to the target methanol content;

[0107] The adjustment module 340 is used to adjust the fuel injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor after the engine operates in the working mode corresponding to the target methanol content, so as to achieve closed-loop control of the excess air coefficient.

[0108] Optionally, the content determination module 330 is further used to:

[0109] Calculate the absolute value of the difference between the current excess air coefficient and the standard excess air coefficient;

[0110] When the absolute value is greater than the first threshold, a correspondence table between historical methanol content and excess air coefficient is obtained, wherein the correspondence table between historical methanol content and excess air coefficient records the correspondence between different methanol contents and excess air coefficients under the working mode corresponding to the historical methanol content;

[0111] Query the corresponding relationship table of historical methanol content and excess air coefficient, and determine the methanol content corresponding to the excess air coefficient with the smallest difference from the current excess air coefficient as the target methanol content;

[0112] When the absolute value is not greater than the first threshold, the historical methanol content is determined as the target methanol content.

[0113] Optionally, the control device 30 of the methanol-gasoline flexible fuel engine further includes:

[0114] The content recording module is used to record the target methanol content so as to control the engine to operate in a working mode corresponding to the target methanol content when the engine is started next time, wherein the methanol content determined under the engine deceleration and fuel cut-off condition is not recorded.

[0115] Optionally, the control device 30 of the methanol-gasoline flexible fuel engine further includes:

[0116] A first determination module, used to determine whether a fueling status signal is obtained before the engine is started;

[0117] The control module 310 is further configured to control the engine to operate in a working mode corresponding to a target methanol content when it is determined that a fueling status signal is obtained.

[0118] Further optionally, the fuel tank is equipped with a fuel heater and a fuel temperature sensor, the fuel temperature sensor is used to monitor the temperature of the methanol-gasoline flexible fuel in the fuel tank, and the fuel heater is used to heat the fuel tank when the temperature collected by the fuel temperature sensor is lower than a temperature threshold;

[0119] The control device 30 of the methanol-gasoline flexible fuel engine also includes:

[0120] A calculation module, for calculating an absolute value of a difference between a target methanol content and a historical methanol content when it is determined that no refueling status signal is obtained and the temperature collected by the fuel temperature sensor is lower than a target temperature;

[0121] The second judgment module is used to judge whether the target methanol content is within a preset methanol content range when the absolute value of the content difference is greater than the stratification threshold, and the methanol content range includes a lower limit value and an upper limit value of the methanol content;

[0122] The control module 310 is further used to control the engine to operate in a working mode corresponding to 100% methanol content when the target methanol content is greater than the upper limit of the methanol content;

[0123] The adjustment module 340 is also used to adjust the fuel injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor after the engine operates in the working mode corresponding to 100% methanol content, so as to achieve closed-loop control of the excess air coefficient.

[0124] Further optionally, the control module 310 is further configured to:

[0125] When the target methanol content is less than the lower limit of the methanol content, the engine is controlled to operate in a working mode corresponding to 0% methanol content;

[0126] The adjustment module 340 is further used for:

[0127] After the engine is running in the working mode corresponding to 0% methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

[0128] Further optionally, the control module 310 is further configured to:

[0129] When the absolute value of the content difference is not greater than the stratification threshold or the target methanol content is within the methanol content range, the engine is controlled to operate in a working mode corresponding to the target methanol content.

[0130] Optionally, the control device 30 of the methanol-gasoline flexible fuel engine further includes:

[0131] The temperature acquisition module is used to obtain the current temperature collected by the fuel temperature sensor;

[0132] The heating module is used to start the fuel heater to heat the methanol-gasoline flexible fuel when the current temperature is lower than the temperature threshold.

[0133] Optionally, the control device 30 of the methanol-gasoline flexible fuel engine further includes:

[0134] A start control module, used for controlling the start of the engine based on a fuel injection correction factor corresponding to a historical methanol content when the engine is started;

[0135] The correction module is used to obtain the excess air coefficient collected by the oxygen sensor during the engine starting process; when the excess air coefficient is less than the second threshold, the injection correction factor is reduced according to the first step length; when the excess air coefficient is greater than the third threshold, the injection correction factor is increased according to the second step length.

[0136] The control device of a methanol-gasoline flexible fuel engine that can be applied to an engine controller provided in the embodiment of the present disclosure can execute the control method of a methanol-gasoline flexible fuel engine provided in the embodiment of the present disclosure, and has the functional modules and beneficial effects corresponding to the execution method. For the contents not fully described in the embodiment of the device of the present disclosure, reference can be made to the description in any method embodiment of the present disclosure.

[0137] The disclosed embodiment also provides an electronic device including a processor and a memory; the processor calls the program or instructions stored in the memory to execute the steps of each embodiment of the control method of the methanol-gasoline flexible fuel engine as described above, which will not be repeated here to avoid repeated description.

[0138] The embodiments of the present disclosure also provide a computer-readable storage medium, which is non-transitory and stores programs or instructions. The programs or instructions enable a computer to execute the steps of the various embodiments of the control method for a methanol-gasoline flexible fuel engine as described above. To avoid repeated description, they will not be repeated here.

[0139] The embodiments of the present disclosure also provide a computer program product, which is used to execute the steps of the various embodiments of the control method of the methanol-gasoline flexible fuel engine as described above.

[0140] The embodiments of the present disclosure also provide a vehicle, comprising the control device of the methanol-gasoline flexible fuel engine as described above, or the electronic device as described above, or the computer-readable storage medium as described above, or the computer program product as described above.

[0141] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0142] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for a methanol-gasoline flexible fuel engine, characterized in that: The method comprises: In response to monitoring that the engine is started, controlling the engine to operate according to an operating mode corresponding to a historical methanol content recorded before the engine was most recently shut down; During the operation of the engine, obtaining a current excess air coefficient collected by a front oxygen sensor; Determining a target methanol content according to a difference between the current excess air coefficient and a standard excess air coefficient; Controlling the engine to operate in a working mode corresponding to the target methanol content; After the engine is operated in the working mode corresponding to the target methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

2. The method according to claim 1, characterized in that: Determining the target methanol content according to the difference between the current excess air coefficient and the standard excess air coefficient includes: Calculating an absolute value of a difference between the current excess air coefficient and the standard excess air coefficient; When the absolute value is greater than the first threshold value, a correspondence table between the historical methanol content and the excess air coefficient is obtained, wherein the correspondence table between the historical methanol content and the excess air coefficient records the correspondence between different methanol contents and the excess air coefficient under the working mode corresponding to the historical methanol content; Querying the correspondence table between the historical methanol content and the excess air coefficient, and determining the methanol content corresponding to the excess air coefficient with the smallest difference from the current excess air coefficient as the target methanol content; When the absolute value is not greater than the first threshold, the historical methanol content is determined to be the target methanol content.

3. The method according to claim 1, characterized in that After adjusting the fuel injection amount of the fuel injector according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient, the method further includes: The target methanol content is recorded to control the engine to operate in a working mode corresponding to the target methanol content when the engine is started next time, wherein the methanol content determined under the engine deceleration and fuel cut-off condition is not recorded.

4. The method according to claim 1, characterized in that: The method further comprises: determining whether a fueling status signal is obtained before the engine is started; When it is determined that the refueling status signal is obtained, the engine is controlled to operate according to the operating mode corresponding to the target methanol content.

5. The method according to claim 4, characterized in that The fuel tank is equipped with a fuel heater and a fuel temperature sensor, wherein the fuel temperature sensor is used to monitor the temperature of the methanol-gasoline flexible fuel in the fuel tank, and the fuel heater is used to heat the fuel tank when the temperature collected by the fuel temperature sensor is lower than a temperature threshold; The method further comprises: When it is determined that the refueling state signal is not obtained and the temperature collected by the fuel temperature sensor is lower than the target temperature, calculating the absolute value of the difference between the target methanol content and the historical methanol content; When the absolute value of the content difference is greater than the stratification threshold, determining whether the target methanol content is within a preset methanol content range, wherein the methanol content range includes a lower limit value of the methanol content and an upper limit value of the methanol content; When the target methanol content is greater than the methanol content upper limit, controlling the engine to operate in a working mode corresponding to 100% methanol content; After the engine is operated in the working mode corresponding to the 100% methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

6. The method according to claim 5, characterized in that The method further comprises: When the target methanol content is less than the lower limit of the methanol content, controlling the engine to operate according to the working mode corresponding to 0% methanol content; After the engine is operated in the working mode corresponding to the 0% methanol content, the fuel injection amount of the injector is adjusted according to the excess air coefficient currently fed back by the front oxygen sensor to achieve closed-loop control of the excess air coefficient.

7. The method according to claim 5, characterized in that The method further comprises: When the absolute value of the content difference is not greater than the stratification threshold or the target methanol content is within the methanol content range, the engine is controlled to operate in a working mode corresponding to the target methanol content.

8. A control device for a methanol-gasoline flexible fuel engine, characterized in that: include: A control module, configured to, in response to detecting engine startup, control the engine to operate in accordance with an operating mode corresponding to a historical methanol content recorded before the engine was most recently shut down; A coefficient acquisition module, used for acquiring a current excess air coefficient collected by a front oxygen sensor during the operation of the engine; A content determination module, used to determine a target methanol content according to a difference between the current excess air coefficient and a standard excess air coefficient; The control module is further used to control the engine to operate in a working mode corresponding to the target methanol content; The adjustment module is used to adjust the fuel injection amount of the injector according to the excess air coefficient currently fed back by the front oxygen sensor after the engine operates in the working mode corresponding to the target methanol content, so as to realize closed-loop control of the excess air coefficient.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a program or instruction, and the program or instruction enables a computer to execute the control method of the methanol-gasoline flexible fuel engine according to any one of claims 1 to 7.

10. A vehicle, characterized in that: It includes the control device of the methanol-gasoline flexible fuel engine as claimed in claim 8, or the computer-readable storage medium as claimed in claim 9.

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