Dual-fuel engine starting method, apparatus, storage medium, and system

Abstract

The application provides a dual-fuel engine starting method, device, storage medium and system, the engine comprising: a methanol injector and a diesel injector, the methanol injector being installed to an air inlet pipe of the engine, and the diesel injector being installed to a cylinder cover of a cylinder of the engine, the method comprising: receiving and responding to an engine starting instruction, acquiring a plurality of temperature parameters, and determining a minimum temperature parameter in all the temperature parameters; when the minimum temperature parameter is less than a preset temperature, controlling the diesel injector to inject a preset first injection amount of diesel into the engine cylinder; determining a speed change rate of a process in which an engine speed changes from static to a first preset speed, and determining a second injection amount of diesel and a third injection amount of methanol according to the speed change rate and simultaneously controlling the diesel injector and the methanol injector to inject, so as to start the engine. The application solves the problem that methanol fuel has low vapor pressure and large latent heat, and thus it is difficult to start the engine at low temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engines, in particular to a dual-fuel engine starting method, a dual-fuel engine starting device, a computer readable storage medium and a dual-fuel engine starting system. BACKGROUND

[0002] Methanol is considered an important direction of internal combustion engine alternative fuel due to its high octane number, fast flame propagation speed and clean renewable characteristics. Existing methanol engines usually supply methanol through intake port injection or in-cylinder direct injection. However, methanol fuel vapor pressure is low, and the latent heat of vaporization is large, which makes it difficult to volatilize in low temperature environment. After being injected into the cylinder, it will absorb a large amount of heat around it, further reducing the cylinder temperature, making it difficult to ignite, and thus affecting the low temperature starting performance of the engine. In addition, the cetane number of methanol is low, and it is difficult to achieve stable ignition by compression self-ignition. If methanol compression ignition method is used alone, the compression ratio needs to be significantly increased, which is difficult in actual application.

[0003] The existing diesel-methanol dual-fuel engine has the problem that methanol is difficult to volatilize and ignite in low temperature environment, resulting in difficulty in starting the engine at low temperature. SUMMARY

[0004] The main purpose of the present application is to provide a dual-fuel engine starting method, a dual-fuel engine starting device, a computer readable storage medium and a dual-fuel engine starting system to at least solve the problem that the low vapor pressure and large latent heat of methanol fuel make it difficult to start the engine at low temperature in the prior art.

[0005] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a dual-fuel engine starting method is provided, the engine comprising a methanol injector and a diesel injector, the methanol injector being installed to an intake pipe of the engine, and the diesel injector being installed to a cylinder head of an engine cylinder, comprising: receiving and responding to an engine starting instruction, acquiring a plurality of temperature parameters, determining the minimum temperature parameter among all the temperature parameters, the temperature parameters including oil temperature, ambient temperature, coolant temperature and intake temperature; when the minimum temperature parameter is less than a preset temperature, controlling the diesel injector to inject a preset first injection amount of diesel into the engine cylinder; determining the speed change rate of the process from the engine speed from static to the first preset speed, and determining the second injection amount of diesel and the third injection amount of methanol according to the speed change rate; controlling the diesel injector and the methanol injector to inject according to the second injection amount and the third injection amount to start the engine.

[0006] Optionally, after obtaining the plurality of temperature parameters in response to the engine start instruction, the method further comprises: in a case where the minimum temperature parameter is greater than or equal to the preset temperature, controlling the methanol injector to inject a preset fourth injection amount of the methanol into the engine cylinder in the compression stroke of the engine, the fourth injection amount being determined based on a working condition of the engine in a case where the minimum temperature parameter is greater than or equal to the preset temperature; controlling the diesel injector to inject the diesel in a case where the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject the methanol.

[0007] Optionally, after controlling the diesel injector to inject the diesel in a case where the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject the methanol, the method further comprises: in a case where the engine speed reaches the first preset speed, determining the speed change rate of the engine, in a case where the speed change rate is greater than a preset speed change rate, obtaining a first difference value between the speed change rate and the preset speed change rate; determining, according to a preset mapping relationship between the first difference value and an injection amount adjustment coefficient, the injection amount adjustment coefficient corresponding to the first difference value, and obtaining a product of the injection amount adjustment coefficient and the first difference value, and determining, based on the product and the fourth injection amount of the methanol, an injection amount of the methanol injector in the next compression stroke of the engine, the first difference value and the injection amount adjustment coefficient corresponding to each other.

[0008] Optionally, the method further comprises: in a case where the speed change rate is less than or equal to the preset speed change rate, obtaining a second difference value between the speed change rate and the preset speed change rate; determining, based on the second difference value, a diesel injection amount correction value and a methanol injection amount correction value in a preset first mapping relationship table, and determining, according to the diesel injection amount correction value and the methanol injection amount correction value, the injection amounts of the diesel injector and the methanol injector in the next compression stroke of the engine, the first mapping relationship table being a mapping relationship table of the second difference value and the diesel injection amount correction value and the methanol injection amount correction value.

[0009] Optionally, determining the second injection amount of the diesel and the third injection amount of the methanol according to the speed change rate comprises: determining, according to a preset second mapping relationship table, the second injection amount of the diesel and the third injection amount of the methanol corresponding to the speed change rate, the second mapping relationship table being a mapping relationship table of the speed change rate and diesel injection amount and methanol injection amount.

[0010] Optionally, before the diesel injector is controlled to inject a preset first injection amount of diesel into the engine cylinder when the minimum temperature parameter is less than a preset temperature, the method further comprises: heating oil of the engine to increase the oil temperature.

[0011] Optionally, the method further comprises: when the engine speed is greater than or equal to a second preset speed, controlling the diesel injector to inject diesel when the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject methanol, so that the methanol is ignited, the second preset speed being used to determine completion of starting of the engine.

[0012] According to another aspect of the present application, a dual-fuel engine starting device is provided, the engine comprising: a methanol injector and a diesel injector, the methanol injector being installed to an intake pipe of the engine, and the diesel injector being installed to a cylinder head of an engine cylinder, comprising: an acquisition unit configured to acquire a plurality of temperature parameters in response to an engine starting instruction, determine a minimum temperature parameter among all the temperature parameters, the temperature parameters comprising an oil temperature, an ambient temperature, a coolant temperature, and an intake temperature; a first control unit configured to control the diesel injector to inject a preset first injection amount of diesel into the engine cylinder when the minimum temperature parameter is less than a preset temperature; a determination unit configured to determine a speed change rate of a process from a standstill to a first preset speed of the engine speed, and determine a second injection amount of diesel and a third injection amount of methanol according to the speed change rate; and a second control unit configured to control the diesel injector and the methanol injector to inject according to the second injection amount and the third injection amount, so as to start the engine.

[0013] According to still another aspect of the present application, a computer readable storage medium is provided, the computer readable storage medium comprising a stored program, wherein the computer readable storage medium controls a device in which the computer readable storage medium is located to perform any one of the methods when the program is executed.

[0014] According to yet another aspect of the present application, a dual-fuel engine starting system is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs comprise instructions for performing any one of the methods.

[0015] The technical scheme of the application is applied to first acquire the engine oil temperature, the ambient temperature, the coolant temperature and the intake air temperature, and determine the minimum temperature parameter; when the minimum temperature parameter is less than the preset temperature, control the diesel injector to inject a preset first injection amount of diesel into the engine cylinder; then determine the speed change rate of the engine speed from the static state to the first preset speed, and determine the second injection amount of diesel and the third injection amount of methanol according to the speed change rate; finally, control the diesel injector and the methanol injector to inject according to the second injection amount and the third injection amount, so as to start the engine. The technical scheme selects the minimum temperature parameter from the engine oil temperature, the ambient temperature, the coolant temperature and the intake air temperature as the judgment basis, avoids the misjudgment caused by a single temperature parameter, and can more truly reflect the most unfavorable condition of the engine starting environment, so that the starting strategy under the low-temperature working condition is more reliable. When the minimum temperature parameter is lower than the preset threshold, the ECU (Electronic Control Unit) controls the diesel injector to inject the first injection amount of diesel, the diesel has high cetane number and good self-ignition performance, and can be more easily compression-ignited in the low-temperature environment, so as to ensure the smooth establishment of combustion and avoid cold start failure. In the process of the engine from the static state to the first preset speed, the speed change rate is calculated, the speed change rate directly reflects whether the engine combustion is sufficient, the larger the speed change rate, the stronger the combustion, the diesel can be reduced, and the methanol can be increased, and the smaller the speed change rate, the weaker the combustion, and the diesel amount needs to be increased to ensure ignition. Therefore, the second injection amount of diesel and the third injection amount of methanol are determined based on the speed change rate, the fuel injection can be more in line with the actual working condition, and energy shortage or waste can be avoided. After the second injection amount and the third injection amount are determined, the diesel injector and the methanol injector are controlled to inject at the same time. The diesel acts as an ignition source to ensure smooth ignition of combustion; the methanol acts as a main fuel to participate in combustion and provide main heat value, so that the engine can establish stable combustion in a short time, ensure that the fuel can be compression-ignited in the cold start stage, and solve the problem that the methanol fuel vapor pressure is low and the latent heat is large, so that the engine is difficult to start at low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the application, and together with the specification explain the application. The use of these drawings in explaining the application is in no way intended as a limitation on the full scope of the application, and the illustrative embodiments described in the drawings are not meant to be not undue limitation on the overall scope of the application. In the drawings:

[0017] Figure 1 A flowchart of a dual-fuel engine starting method according to an embodiment of the application is shown;

[0018] Figure 2 A structural diagram of a dual-fuel engine according to an embodiment of the application is shown;

[0019] Figure 3A flow chart of a dual-fuel engine starting control method under normal temperature working condition is shown according to an embodiment of the present application;

[0020] Figure 4 A flow chart of a dual-fuel engine starting control method based on a change rate of rotation speed is shown according to an embodiment of the present application;

[0021] Figure 5 A flow chart of a method for determining a correction value of injection amount is shown according to an embodiment of the present application;

[0022] Figure 6 A structure block diagram of a dual-fuel engine starting device is shown according to an embodiment of the present application.

[0023] Among the above drawings, the following reference signs are included:

[0024] 100, methanol injector; 200, diesel injector. DETAILED DESCRIPTION

[0025] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0026] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0027] It should be noted that the terms "first", "second" and the like in the specification 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 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 limit to those clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0028] As introduced in the background, the prior art has the problem of low methanol fuel vapor pressure and large latent heat, which leads to the difficulty in starting the engine at low temperature. To solve the above technical problem, the embodiments of the present application provide a dual-fuel engine starting method, a dual-fuel engine starting device, a computer readable storage medium and a dual-fuel engine starting system.

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0030] Figure 1 is a flowchart of the dual-fuel engine starting method according to the embodiments of the present application. Figure 2 is a structural schematic diagram of a dual-fuel engine. As shown in Figure 2 , the engine comprises a methanol injector 100 and a diesel injector 200. The methanol injector 100 is installed to the intake pipe of the engine, and the diesel injector 200 is installed to the cylinder head of the engine cylinder. As shown in Figure 1 , the method comprises the following steps:

[0031] Step S101, receiving and responding to an engine starting instruction, obtaining a plurality of temperature parameters, determining the minimum temperature parameter among all the temperature parameters, and the temperature parameters include oil temperature, ambient temperature, coolant temperature and intake temperature;

[0032] Step S102, when the minimum temperature parameter is less than a preset temperature, controlling the diesel injector 200 to inject a preset first injection amount of diesel into the engine cylinder;

[0033] Specifically, the first injection amount of diesel is injected at the end of the compression stroke when the piston approaches the top dead center. The first injection amount has been determined at the engine calibration, which can ensure that sufficient compression heat source can be generated even under low temperature conditions.

[0034] Step S103, determining the speed change rate of the process from the engine speed from static to the first preset speed, and determining the second injection amount of diesel and the third injection amount of methanol according to the speed change rate;

[0035] Specifically, after the engine receives the starting instruction, the crankshaft speed signal is continuously collected from the engine static, i.e. the speed is 0, and the sampling frequency is generally in the order of milliseconds, for example, 1ms-5ms. When the engine speed rises from 0 to the first preset speed, the sampling is ended, thereby obtaining the speed curve in the starting stage. The speed change rate is obtained by analyzing the steepness of the speed curve in the starting stage.

[0036] Step S104, according to the above-mentioned second injection amount and the above-mentioned third injection amount, simultaneously control the above-mentioned diesel injector 200 and the above-mentioned methanol injector 100 to inject, so as to start the above-mentioned engine.

[0037] Specifically, the diesel injection signal is triggered at the end of the compression stroke, when the piston is close to the top dead center, and the methanol can be injected synchronously with the diesel or injected after the diesel combustion is established.

[0038] Through the above-mentioned embodiment, first, the oil temperature, the ambient temperature, the coolant temperature and the intake temperature are acquired, and the minimum temperature parameter is determined; when the minimum temperature parameter is less than the preset temperature, the diesel injector is controlled to inject a preset first injection amount of diesel into the engine cylinder; then the speed change rate of the engine speed from static to the first preset speed is determined, and the second injection amount of diesel and the third injection amount of methanol are determined according to the speed change rate; finally, the diesel injector and the methanol injector are simultaneously controlled to inject according to the second injection amount and the third injection amount, so as to start the engine. The scheme avoids misjudgment caused by a single temperature parameter by simultaneously collecting the oil temperature, the ambient temperature, the coolant temperature and the intake temperature, and selecting the minimum temperature parameter as the judgment basis, so that the most unfavorable condition of the engine starting environment can be more truly reflected, and the starting strategy under low temperature working condition is more reliable. When the minimum temperature parameter is lower than the preset threshold, the ECU (Electronic Control Unit) controls the diesel injector to inject the first injection amount of diesel, and the diesel has a high cetane number and good self-ignition performance, which can be more easily compression-ignited in a low temperature environment, thereby ensuring smooth combustion and avoiding cold start failure. In the process of the engine from static to the first preset speed, the speed change rate is calculated, which directly reflects whether the engine combustion is sufficient. The larger the speed change rate, the stronger the combustion, and the diesel can be reduced and the methanol can be increased. The smaller the speed change rate, the weaker the combustion, and the diesel amount needs to be increased to ensure ignition. Therefore, based on the speed change rate, the second injection amount of diesel and the third injection amount of methanol are determined, which can make the fuel injection more in line with the actual working condition, and avoid energy deficiency or waste. After the second injection amount and the third injection amount are determined, the diesel injector and the methanol injector are simultaneously controlled to inject. The diesel acts as an ignition source to ensure smooth ignition; the methanol acts as a main fuel to participate in combustion and provide the main heat value, so that the engine can establish stable combustion in a short time, and ensure that the fuel can be compression-ignited in the cold start stage, thereby solving the problem that the methanol fuel vapor pressure is low and the latent heat is large, which makes it difficult for the engine to start at low temperature.

[0039] The preset first injection amount is a reference diesel injection amount of the engine under a cold start condition. Its determination method usually includes the following: based on engine bench calibration test, engine cold start test is carried out under different environmental temperatures, diesel injection amount is adjusted step by step until the engine can be ignited smoothly and kept running, and the lowest feasible and stable ignition injection amount in the test is taken as the reference injection amount under the temperature condition. Calculate the minimum combustion heat value required by the engine during the starting stage; combine the low heat value of diesel and the flow characteristics of the injector to obtain the required fuel mass flow; take it as the theoretical calculation basis of the first injection amount. On the basis of bench calibration or calculation value, usually a safety margin of 5%-10% is added to prevent ignition failure due to low oil temperature and poor atomization, for example: for a 2.0L dual-fuel engine, when the environmental temperature is-10℃, the test shows that the minimum diesel injection amount required for starting is 20mg / cycle, considering the influence of high oil viscosity and injector delay, the preset first injection amount is finally set to 22mg / cycle, so as to ensure reliable ignition at low temperature while avoiding excessive diesel injection to cause soot emission and nozzle carbon deposition.

[0040] In an alternative, as shown in FIG. 5, after obtaining a plurality of temperature parameters in response to an engine start instruction, the above method further comprises: Figure 3

[0041] Step S201, in the case where the minimum temperature parameter is greater than or equal to the preset temperature, controlling the methanol injector to inject a preset fourth injection amount of the methanol into the cylinder of the engine during the compression stroke of the engine, the fourth injection amount being determined based on the working condition of the engine when the minimum temperature parameter is greater than or equal to the preset temperature;

[0042] Step S202, controlling the diesel injector to inject the diesel when the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject the methanol, the preset position being located before the top dead center of the piston.

[0043] ​In the above embodiments, when the engine's minimum temperature parameter is greater than or equal to a preset temperature, a fourth injection quantity of methanol, preset according to the operating conditions, is injected during the compression stroke to ensure thorough atomization and mixing, preparing for subsequent combustion. Subsequently, diesel fuel is injected at a preset position before the piston reaches top dead center. The diesel fuel spontaneously combusts under high temperature and pressure, forming a flame nucleus that immediately ignites the pre-installed methanol and the additionally injected methanol, thereby rapidly establishing a strong and stable combustion process and achieving reliable engine starting. By using a methanol-diesel-methanol injection mode at room temperature, methanol provides the primary calorific value. Because methanol rapidly participates in combustion under the action of the diesel flame, it can release a large amount of heat in a very short time, thus establishing a strong and stable combustion process. This ensures rapid engine starting under room temperature conditions, shortens start-up time, and allows methanol to function as the primary fuel, reducing dependence on diesel fuel and further improving combustion efficiency and emission performance.

[0044] The reference value for the fourth injection quantity was determined based on bench calibration test data.

[0045] In another alternative, such as Figure 4 As shown, after controlling the diesel injector to inject diesel fuel when the piston reaches a preset position to ignite the diesel fuel, and controlling the methanol injector to inject methanol, the method further includes:

[0046] Step S301: When the engine speed reaches the first preset speed, determine the engine speed change rate; when the speed change rate is greater than the preset speed change rate, obtain the first difference between the speed change rate and the preset speed change rate.

[0047] Step S302: Based on the preset mapping relationship between the first difference and the injection quantity adjustment coefficient, determine the injection quantity adjustment coefficient corresponding to the first difference, obtain the product of the injection quantity adjustment coefficient and the first difference, and determine the injection quantity of the methanol injector in the compression stroke of the next engine based on the product and the fourth injection quantity of methanol. The first difference and the injection quantity adjustment coefficient are in one-to-one correspondence.

[0048] In the above embodiment, after the engine speed reaches the first preset speed, the speed change rate of the engine is obtained and compared with the preset speed change rate. When the actual speed change rate is greater than the preset speed change rate, the difference between the two is determined, and the corresponding injection amount adjustment coefficient is found in the mapping relationship table according to the difference. The fourth preset injection amount is corrected according to the product of the adjustment coefficient and the difference, so as to obtain the methanol injection amount for the next compression stroke. In the above manner, the methanol injection amount can be timely reduced in the case that the engine combustion is too intense and the speed rises too fast, so as to avoid the problem of unstable combustion caused by too fast heat release, so as to keep the engine in a stable speed rising trend during the starting process, and improve the smoothness and stability of the starting process. At the same time, since the correction amount is one-to-one corresponding to the difference, the certainty and repeatability of the adjustment process are ensured, which is beneficial to achieving consistent starting effect under different working conditions and different environmental conditions.

[0049] Specifically, the injection amount of the methanol injector in the next compression stroke of the engine is determined according to Q2=Q1×(1−k·Δr), wherein Q1 is the methanol injection amount before adjustment, Q2 is the methanol injection amount after adjustment, and Δr is the first difference.

[0050] In some exemplary embodiments, as shown in Figure 5 The above method further comprises:

[0051] In step S401, in the case that the speed change rate is less than or equal to the preset speed change rate, a second difference between the speed change rate and the preset speed change rate is obtained.

[0052] In step S402, based on the second difference, a diesel injection amount correction value and a methanol injection amount correction value are determined in a first preset mapping relationship table, and the injection amounts of the methanol injector and the diesel injector in the next compression stroke of the engine are determined according to the diesel injection amount correction value and the methanol injection amount correction value. The first mapping relationship table is a mapping relationship table of the second difference and the diesel injection amount correction value and the methanol injection amount correction value.

[0053] In the above embodiment, by obtaining the second difference value between the speed change rate and the preset speed change rate when the speed change rate is less than or equal to the preset speed change rate, and determining the diesel injection amount correction value and the methanol injection amount correction value in the preset mapping relationship table by using the difference value, adaptive compensation of the fuel injection amount is realized. When the combustion intensity is insufficient and the speed rises slowly during engine starting, the diesel injection amount and the methanol injection amount can be automatically increased according to the difference value, so that the diesel can still be reliably ignited, and the methanol can obtain sufficient opportunity to participate in combustion, thereby improving the combustion heat release level. By compensating the injection amount, the engine speed climbing delay or starting failure caused by insufficient combustion is avoided, the starting time is shortened, the diesel injection amount correction value ensures stable ignition, the methanol injection amount correction value ensures continuous combustion, and the combination of the two makes the combustion process more stable. Since the second difference value and the injection amount correction value are one-to-one corresponding, the predictability and consistency of the compensation are ensured, and random adjustment does not occur. In addition, it can also automatically adapt to different environmental temperatures, engine wear degrees or fuel quality differences. The above method compensates the dual fuel based on the difference value, so that the engine can quickly recover the required combustion intensity in the next cycle, ensure smooth starting, and further solve the problem that the engine is difficult to start at low temperature.

[0054] Specifically, the first mapping relationship table is a lookup table data stored in advance in the engine control unit, and is used to represent the corresponding relationship between the speed change rate and the diesel injection amount correction value and the methanol injection amount correction value. The first mapping relationship table specifies that when the speed change rate is low, how much diesel injection amount and how much methanol injection amount need to be increased; when the deviation is large, the correction amount also increases accordingly. The first mapping relationship table is obtained by performing engine starting experiments under different environmental temperatures, speeds and load conditions. The speed curve during starting is recorded, and the speed change rate is calculated. At the same time, the diesel and methanol injection amounts are adjusted, and whether the engine can start smoothly is observed. The injection correction value that can ensure successful starting is corresponded to the speed change rate difference at that time to form a data point. The test data is classified, for example: when the speed change rate is only slightly lower than the preset value, the diesel correction amount is +2 mg / cycle, and the methanol correction amount is +3 mg / cycle; when the speed change rate is significantly lower than the preset value, the diesel correction amount is +5 mg / cycle, and the methanol correction amount is +7 mg / cycle. Thus, a plurality of corresponding relationships between the second difference value and the diesel correction value and the methanol correction value are obtained, a mapping table is formed and stored in the ECU, and the first mapping relationship table is obtained.

[0055] In some example embodiments, the second injection amount of diesel and the third injection amount of methanol are determined according to the rate of change of the engine speed, including: determining the second injection amount of diesel and the third injection amount of methanol corresponding to the rate of change of the engine speed according to a preset second mapping relationship table, the second mapping relationship table being a mapping relationship table of the rate of change of the engine speed and the injection amount of diesel and the injection amount of methanol.

[0056] In the above embodiments, by introducing the second mapping relationship table, a one-to-one correspondence between the rate of change of the engine speed and the injection amount of diesel and the injection amount of methanol is established. When the rate of change of the engine speed is low, it indicates that the combustion reaction is insufficient, and according to the second mapping relationship table, the injection amount of diesel is increased to ensure stable ignition. At the same time, the injection amount of methanol is appropriately reduced to avoid excessive heat absorption to inhibit ignition, thereby improving ignition reliability. When the rate of change of the engine speed is in a reasonable range, the injection amount of diesel and the injection amount of methanol given by the second mapping relationship table are maintained at the optimal ratio calibrated, ensuring that the engine speed rising process is smooth and does not appear to be jittery or delayed. When the rate of change of the engine speed is high, it indicates that the combustion heat release is too strong, and according to the mapping relationship table, the injection amount of diesel can be reduced and the injection amount of methanol can be increased to utilize the high latent heat characteristics of methanol to reduce the in-cylinder temperature rise, achieve more uniform combustion, and improve thermal efficiency. Since the second mapping relationship table is established in the process of bench testing and calibration, it covers a variety of starting conditions, and its results are universal. Using the second mapping relationship table to determine the second injection amount of diesel and the third injection amount of methanol can dynamically allocate the injection ratio of diesel and methanol according to the actual rate of change of the engine speed, ensuring that diesel provides reliable ignition and fully utilizes the role of methanol as a main fuel, thereby achieving fast, stable, and low-emission engine starting.

[0057] Specifically, the second mapping relationship table is used to represent the correspondence between the rate of change of the engine speed, the second injection amount of diesel, and the third injection amount of methanol. When the ECU detects that the rate of change of the engine speed is at different levels, the optimal combination of the injection amount of diesel and the injection amount of methanol can be quickly obtained by table lookup, thereby ensuring the stability and efficiency of engine combustion during the starting stage. The second mapping relationship table is obtained by conducting engine starting experiments under different speeds, loads, and ambient temperatures. The rate of change of the speed during the starting stage is recorded, and the combustion under different injection combinations is tested to find the optimal diesel / methanol injection ratio that can ensure smooth engine starting. The rate of change of the speed is taken as the input condition, and the corresponding optimal injection amount of diesel and the injection amount of methanol are taken as the output results. The data is segmented or fitted to form a corresponding relationship table of input and output. The calibrated and verified corresponding relationship table is solidified into the ECU program. During the starting process, the ECU directly looks up the corresponding second injection amount of diesel and the third injection amount of methanol according to the real-time measured rate of change of the speed.

[0058] In some example solutions of the present application, when the minimum temperature parameter is less than the preset temperature, before the diesel injector is controlled to inject the preset first injection amount of diesel into the engine cylinder, the method further includes: heating the engine oil to increase the oil temperature.

[0059] In the above embodiment, by preheating the engine oil under low temperature conditions, the oil temperature is increased, which can significantly improve the reliability and stability of the engine starting process. In a low temperature environment, the viscosity of the oil increases, and the engine generates a large frictional resistance when starting, which causes the starter load to increase and the engine speed to climb difficultly. By preheating the oil, the viscosity decreases, the lubricating oil film is quickly established, and the frictional resistance decreases, making the engine easier to be driven during the starting stage. The diesel injection amount during the starting stage is limited, and if the mechanical resistance is too large, the in-cylinder compression temperature and pressure are difficult to quickly reach the requirements for diesel self-ignition. The oil preheating reduces the resistance, making the compression process more efficient and ensuring that the diesel can be reliably ignited at the first injection amount. Moreover, since the oil preheating improves the mechanical operating state of the engine, the engine can reach the set speed more quickly, shortening the starting time in a low temperature environment and further solving the problem of difficult engine starting in a low temperature environment.

[0060] In yet some example solutions of the present application, the method further includes: when the engine speed is greater than or equal to a second preset speed, controlling the diesel injector to inject diesel when the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject methanol, so that the methanol is ignited, the second preset speed being used to determine that the engine completes starting.

[0061] In the above embodiment, by triggering the control when the engine speed is greater than or equal to the second preset speed, the starting stage and the normal running stage can be clearly distinguished. When the engine reaches the second preset speed, the ECU controls the diesel injector to inject diesel when the piston approaches the top dead center of the piston, ensuring that the diesel reliably self-ignites under high temperature and high pressure conditions; at the same time, the methanol injector is controlled to inject methanol, so that the methanol is rapidly ignited and participates in the main combustion relying on the diesel flame. By using the second preset speed as a criterion, it can be clearly identified that the engine has entered a self-sustaining combustion state, avoiding misjudgment or premature switching of the injection mode. The diesel self-ignites at the compression end to form a flame kernel, ensuring reliable ignition, and the methanol participates in combustion in large quantities under the ignition of the diesel flame, releasing additional energy to help the engine quickly transition from starting to stable operation and shorten the starting time. Since the diesel injection amount is relatively reduced, the methanol as a clean fuel provides more energy, which can reduce the soot emission during the starting process.

[0062] In order for those skilled in the art to more clearly understand the technical solutions of the present application, the implementation process of the dual-fuel engine starting method of the present application will be described in detail below in conjunction with specific embodiments.

[0063] The present embodiment relates to a specific dual-fuel engine starting method. Since the cetane number of methanol fuel is low, it is difficult to simply rely on compression ignition of methanol, and therefore a diesel-methanol dual-fuel direct injection engine generally adopts a mode of diesel compression ignition to ignite methanol to achieve starting. Since the diesel injection amount required during engine starting stage is large, and diesel combustion is not sufficient and tends to produce soot, there is a risk of injector clogging. In order to reduce the risk of injector clogging, it is necessary to reduce the diesel injection amount during starting as much as possible. When the ambient temperature is lower than the preset temperature, there is a large uncertainty in diesel compression ignition starting under low temperature environment. Before injecting diesel, if methanol fuel is pre-injected into the cylinder, due to the large latent heat of vaporization of methanol fuel, the cylinder temperature is easily further reduced, which is more unfavorable for diesel compression ignition, and there is a risk of starting failure. Therefore, when the ambient temperature is lower than the value, the diesel-methanol dual direct injection engine starting process adopts: diesel-methanol injection mode. First, diesel is injected, and when the ECU detects that the engine speed exceeds the starter exit speed, the diesel injection amount is reduced, and methanol injection is controlled. When the ambient temperature is higher than the preset temperature, in order to improve the engine starting effect, the methanol-diesel-methanol injection mode is adopted. The large heat release rate generated in this mode is used to achieve rapid combustion in the engine cylinder. During the starter reverse drag engine stage, the ECU controls the methanol injector to pre-inject part of the methanol fuel into the cylinder, and diesel is injected when the piston approaches the top dead center. Since diesel has a high cetane number and is easy to be compression ignited, when diesel is compression ignited, the pre-injected methanol fuel in the cylinder is also ignited. When the ECU monitors that the engine speed change rate exceeds the set value, the methanol pre-injection amount is reduced in the next cycle, and when the engine starts successfully, the injection mode is switched to the mode of first injecting diesel and then injecting methanol.

[0064] The embodiments of the present application also provide a specific implementation scenario of determining the methanol injection amount of the next stroke according to the engine speed change rate. When the engine is in a normal temperature starting condition, the ECU first injects a certain amount of methanol in the compression stroke, and injects diesel before the piston approaches the top dead center to achieve reliable ignition. Subsequently, when the engine speed reaches a first preset speed, the difference Δr between the actual speed change rate and the preset speed change rate is calculated, and the corresponding injection amount adjustment coefficient k is determined by looking up the table. If the methanol reference injection amount Q1 of the current cycle is 14.0 mg / cycle, the actual detected Δr is 0.15, and the k value is 0.3, then the ECU calculates the methanol injection amount Q2 of the next compression stroke according to the formula Q2=Q1×(1−k·Δr) Q2=13.37 mg / cycle. It can be seen that when the speed change rate is high, the ECU automatically reduces the methanol injection amount of the next stroke to avoid too intense combustion causing the speed to climb too fast. If Δr reaches 0.3 and k is 0.5, the calculated Q2 is 11.90 mg / cycle, but since it exceeds the calibrated maximum single-cycle reduction of 10%, the ECU will limit the processing, correct Q2 to 12.60 mg / cycle, and continue to gradually correct in the subsequent cycles. In this way, the methanol injection amount can be dynamically adjusted based on the speed change rate feedback in each cycle, so that the engine can quickly establish combustion during the starting process, and avoid instability caused by excessive heat release, achieving smooth and reliable starting.

[0065] The embodiment of the present application further provides a specific implementation scenario of engine starting in a diesel-methanol mode, in which the engine is equipped with a methanol injector installed on an intake pipe and a diesel injector installed on a cylinder head. When the engine is started in a normal temperature environment, a certain amount of methanol fuel is first injected by the methanol injector in a compression stroke, and diesel is injected when the piston approaches a preset position of a top dead center. The diesel is ignited rapidly due to its high cetane number, forming a flame kernel, thereby igniting the already injected methanol fuel in the cylinder and prompting the engine to complete initial combustion. When the engine speed gradually increases and reaches a second preset speed, it is determined that the engine has the self-sustaining combustion capability, and then enters a injection mode switching stage. In this stage, the ECU controls the diesel injector to inject diesel when the piston reaches the preset position, to ensure stable ignition, and controls the methanol injector to inject methanol after the diesel flame is established, so that the methanol is rapidly ignited and fully combusted, thereby releasing more energy in the starting stage and promoting the engine to quickly enter a stable running state. Through the above scheme, the second preset speed is used as a criterion to accurately distinguish whether the engine has completed starting, the ignition reliability is ensured by the ignition of diesel at the compression end, the methanol is fully combusted under the ignition of the flame kernel, the combustion efficiency and stability are improved, and in addition, the strategy of mainly combusting methanol and secondarily igniting diesel after the engine completes starting effectively reduces the diesel consumption, reduces the soot emission, and improves the environmental protection performance.

[0066] It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described herein can be executed in an order different from that shown.

[0067] The embodiment of the present application further provides a dual-fuel engine starting device. It should be noted that the dual-fuel engine starting device of the embodiment of the present application can be used to execute the dual-fuel engine starting method provided by the embodiment of the present application. The device is used to realize the above-mentioned embodiments and preferred embodiments, and will not be described again. As used below, the term "module" can be a combination of software and / or hardware that realizes a predetermined function. Although the device described in the following embodiments is preferably realized in software, hardware, or a combination of software and hardware is also possible and contemplated.

[0068] The dual-fuel engine starting device provided by the embodiment of the present application is described below.

[0069] Figure 6 is a schematic diagram of the dual-fuel engine starting device according to the embodiment of the present application. As shown in Figure 6 , the device includes:

[0070] The first acquisition unit 10 is configured to receive and respond to an engine starting instruction, acquire a plurality of temperature parameters, and determine a minimum temperature parameter among all the temperature parameters, wherein the temperature parameters include engine oil temperature, ambient temperature, coolant temperature, and intake air temperature.

[0071] The first control unit 20 is configured to control the diesel injector to inject a preset first injection amount of diesel into the engine cylinder when the minimum temperature parameter is less than a preset temperature.

[0072] Specifically, the preset first injection amount of diesel is injected when the piston approaches the top dead center at the end of the compression stroke, and the first injection amount is determined during engine calibration to ensure that sufficient compression heat source can be generated even under low temperature conditions.

[0073] The first determination unit 30 is configured to determine the speed change rate of the engine speed from static to the first preset speed, and determine the second injection amount of diesel and the third injection amount of methanol according to the speed change rate.

[0074] Specifically, after the engine receives the starting instruction, the crankshaft speed signal is continuously collected from the engine static state, i.e. the speed is 0, and the sampling frequency is generally in the order of milliseconds, for example, 1ms-5ms. When the engine speed rises from 0 to the first preset speed, the sampling is ended, thereby obtaining the speed curve of the starting stage, and the speed change rate is obtained by analyzing the steepness of the starting stage speed curve.

[0075] The second control unit 40 is configured to control the diesel injector and the methanol injector to start the engine according to the second injection amount and the third injection amount.

[0076] Specifically, the diesel injection signal is triggered at the end of the compression stroke when the piston approaches the top dead center, and the methanol can be injected synchronously with the diesel or injected after the diesel combustion is established.

[0077] Through the above embodiment, first, the oil temperature, the ambient temperature, the coolant temperature and the intake temperature are acquired by the first acquisition unit, and the minimum temperature parameter is determined; when the minimum temperature parameter is less than the preset temperature, the first control unit controls the diesel injector to inject a preset first injection amount of diesel into the engine cylinder; then the first determination unit determines the speed change rate of the engine speed from static to the first preset speed, and determines the second injection amount of diesel and the third injection amount of methanol according to the speed change rate; finally, the second control unit controls the diesel injector and the methanol injector to inject according to the second injection amount and the third injection amount, so as to start the engine. The scheme collects the oil temperature, the ambient temperature, the coolant temperature and the intake temperature at the same time, and selects the minimum temperature parameter as the judgment basis, which avoids the misjudgment caused by a single temperature parameter, so that the most unfavorable condition of the engine starting environment can be more truly reflected, and the starting strategy under low temperature working condition is more reliable. When the minimum temperature parameter is lower than the preset threshold, the ECU controls the diesel injector to inject the first injection amount of diesel, and the diesel has high cetane number and good self-ignition performance, which can be more easily compression-ignited in low temperature environment, so as to ensure the smooth establishment of combustion and avoid cold start failure. In the process of the engine from static to the first preset speed, the speed change rate is calculated, which directly reflects whether the engine combustion is sufficient. The larger the speed change rate is, the stronger the combustion is, and the diesel can be reduced and the methanol can be increased. The smaller the speed change rate is, the weaker the combustion is, and the diesel amount needs to be increased to ensure ignition. Therefore, the second injection amount of diesel and the third injection amount of methanol are determined based on the speed change rate, which can make the fuel injection more in line with the actual working condition, and avoid energy deficiency or waste. After the second injection amount and the third injection amount are determined, the diesel injector and the methanol injector are controlled to inject at the same time. The diesel acts as an ignition source to ensure smooth ignition; the methanol acts as a main fuel to participate in combustion and provide main heat value, so that the engine can establish stable combustion in a short time, and ensure that the fuel can be compression-ignited in the cold start stage, thereby solving the problem that the methanol fuel vapor pressure is low and the latent heat is large, which makes it difficult for the engine to start at low temperature.

[0078] In an alternative, the device further comprises: a third control unit, configured to control the methanol injector to inject a preset fourth injection amount of the methanol into the engine cylinder during the compression stroke of the engine when the minimum temperature parameter is greater than or equal to the preset temperature, the fourth injection amount being determined based on the working condition of the engine when the minimum temperature parameter is greater than or equal to the preset temperature; and a fourth control unit, configured to control the diesel injector to inject the diesel when the piston reaches a preset position, so that the diesel is ignited, and control the methanol injector to inject the methanol, the preset position being located before the top dead center of the piston.

[0079] In the above embodiments, when the minimum engine temperature parameter is greater than or equal to the preset temperature, the fourth injection amount of methanol preset according to the working condition is injected in the compression stroke to make it fully atomized and mixed, so as to prepare for the subsequent combustion; then diesel is injected at a preset position before the piston reaches the top dead center, the diesel self-ignites to form a flame kernel under high temperature and high pressure, and immediately ignites the pre-set methanol and the additional injected methanol, so as to quickly establish a strong and stable combustion process, and realize reliable starting of the engine. Through the methanol-diesel-methanol injection mode at normal temperature, the main heat value is provided by methanol, and since the methanol rapidly participates in combustion under the action of the diesel flame, a large amount of heat can be released in a very short time, so as to establish a strong and stable combustion process, ensure the rapid starting of the engine under normal temperature conditions, shorten the starting time, and enable the methanol to play a role as the main fuel, reduce the dependence on the amount of diesel, and further improve the combustion efficiency and emission performance.

[0080] The fourth injection amount is determined based on the bench calibration test data.

[0081] In another alternative, the device further comprises: a second determination unit configured to determine the engine speed change rate when the engine speed reaches the first preset speed, and obtain a first difference between the speed change rate and a preset speed change rate when the speed change rate is greater than the preset speed change rate; and a third determination unit configured to determine the injection amount adjustment coefficient corresponding to the first difference according to a preset mapping relationship between the first difference and the injection amount adjustment coefficient, obtain the product of the injection amount adjustment coefficient and the first difference, and determine the injection amount of the methanol injector in the compression stroke of the next engine according to the product and the fourth injection amount of the methanol. The first difference and the injection amount adjustment coefficient correspond to each other.

[0082] In the above embodiments, after the engine speed reaches the first preset speed, the speed change rate of the engine is obtained and compared with the preset speed change rate, and when the actual speed change rate is greater than the preset speed change rate, the difference between them is determined, and the corresponding injection amount adjustment coefficient is found in the mapping relationship table according to the difference. The fourth injection amount is corrected according to the product of the adjustment coefficient and the difference, so as to obtain the methanol injection amount for the next compression stroke. By using the above method, the methanol injection amount can be timely reduced when the engine combustion is too intense and the speed rises too fast, so as to avoid the problem of unstable combustion caused by too fast heat release, and keep the engine speed rising steadily during starting, thereby improving the smoothness and stability of starting. At the same time, since the correction amount corresponds to the difference one by one, the determinacy and repeatability of the adjustment process are ensured, which is beneficial to achieving consistent starting effect under different working conditions and different environmental conditions.

[0083] Specifically, the injection amount of the methanol injector in the compression stroke of the next engine is determined according to Q2=Q1×(1−k·Δr), where Q1 is the injection amount of the methanol before adjustment, Q2 is the injection amount of the methanol after adjustment, and Δr is the first difference value.

[0084] In some example embodiments, the device further comprises: a second acquisition unit configured to acquire a second difference value between the rotational speed change rate and the preset rotational speed change rate when the rotational speed change rate is less than or equal to the preset rotational speed change rate; and a fourth determination unit configured to determine the diesel injection amount correction value and the methanol injection amount correction value in a preset first mapping relationship table based on the second difference value, and determine the injection amounts of the diesel injector and the methanol injector in the compression stroke of the next engine according to the diesel injection amount correction value and the methanol injection amount correction value, the first mapping relationship table being a mapping relationship table of the second difference value, the diesel injection amount correction value, and the methanol injection amount correction value.

[0085] In the above embodiments, when the rotational speed change rate is less than or equal to the preset rotational speed change rate, the second difference value between the rotational speed change rate and the preset rotational speed change rate is acquired, and the diesel injection amount correction value and the methanol injection amount correction value are determined in the preset mapping relationship table using the difference value, thereby achieving adaptive compensation of the fuel injection amount. When the engine has insufficient combustion intensity and the rotational speed rises slowly during the starting process, the diesel injection amount and the methanol injection amount can be automatically increased according to the difference value, so as to ensure that the diesel can be reliably ignited and the methanol has enough opportunity to participate in combustion, thereby improving the combustion heat release level. By compensating the injection amount, the engine speed climbing delay or starting failure caused by insufficient combustion is avoided, the starting time is shortened, the diesel injection amount correction value ensures stable ignition, the methanol injection amount correction value ensures sustained combustion, and the combination of the two makes the combustion process more stable. Since the second difference value and the injection amount correction value correspond to each other, the predictability and consistency of the compensation are ensured, and random adjustment does not occur. In addition, the method can automatically adapt to different environmental temperatures, engine wear degrees, or fuel quality differences. The above method compensates the dual fuels based on the difference value, so that the engine can quickly recover the required combustion intensity in the next cycle, ensure smooth starting, and further solve the problem that the engine is difficult to start at low temperature.

[0086] In other example embodiments, the first determination unit comprises a determination module configured to determine the second injection amount of the diesel and the third injection amount of the methanol corresponding to the rotational speed change rate according to a preset second mapping relationship table, the second mapping relationship table being a mapping relationship table of the rotational speed change rate, the diesel injection amount, and the methanol injection amount.

[0087] In the above embodiment, by introducing the second mapping relationship table, the engine speed change rate is established one-to-one correspondence with the diesel injection amount and the methanol injection amount. When the speed change rate is low, it indicates that the combustion reaction is insufficient, and according to the second mapping relationship table, the diesel injection amount is increased to ensure stable ignition. At the same time, the methanol injection amount is appropriately reduced to avoid excessive heat absorption to inhibit ignition, thereby improving the ignition reliability. When the speed change rate is in a reasonable interval, the diesel and methanol injection amounts given by the second mapping relationship table are maintained at the optimal ratio calibrated, ensuring that the engine speed rising process is smooth and does not appear to be jittering or delayed. When the speed change rate is high, it indicates that the combustion heat release is too strong, and the diesel injection amount can be reduced and the methanol injection amount can be increased according to the mapping relationship table, using the high latent heat characteristics of methanol to reduce the in-cylinder temperature rise, achieve more uniform combustion, and improve thermal efficiency. Since the second mapping relationship table is established in the bench test and calibration process, it covers a variety of starting conditions, and its results are universal. Using the second mapping relationship table to determine the second diesel injection amount and the third methanol injection amount can dynamically allocate the injection ratio of diesel and methanol according to the actual engine speed change rate, ensuring that diesel provides reliable ignition and fully utilizes the role of methanol as the main fuel, thereby realizing fast, stable and low-emission engine starting.

[0088] In some example schemes of the present application, the device further comprises a heating unit for heating the engine oil to increase the oil temperature.

[0089] In the above embodiment, by preheating the engine oil under low temperature conditions, the oil temperature is raised, which can significantly improve the reliability and stability of the engine starting process. In a low temperature environment, the viscosity of the oil increases, and the engine will generate a large frictional resistance when starting, resulting in an increased starter load and difficulty in climbing the engine speed. By preheating the oil, the viscosity is reduced, the lubricating oil film is quickly established, and the frictional resistance is reduced, making it easier for the engine to be driven during the starting stage. The diesel injection amount during the starting stage is limited, and if the mechanical resistance is too large, the in-cylinder compression temperature and pressure will be difficult to quickly reach the requirements for diesel self-ignition. Preheating the oil reduces the resistance, making the compression process more efficient and ensuring that the diesel can reliably ignite at the first injection amount. Moreover, since the preheating of the oil improves the mechanical operating state of the engine, the engine can reach the set speed faster, shortening the starting time in a low temperature environment and further solving the problem of difficult engine starting in a low temperature environment.

[0090] In yet some example schemes of the present application, the transposition further comprises a fifth control unit for controlling the diesel injector to inject diesel when the piston reaches a preset position to ignite the diesel, and controlling the methanol injector to inject methanol to ignite the methanol, when the engine speed is greater than or equal to a second preset speed, the second preset speed being used to determine that the engine completes starting.

[0091] In the above embodiment, by triggering the control when the engine speed is greater than or equal to the second preset speed, the starting stage and the normal running stage can be clearly distinguished. When the engine reaches the second preset speed, the ECU controls the diesel injector to inject diesel at a preset position where the piston is close to the top dead center, ensuring that the diesel reliably self-ignites under high temperature and high pressure conditions; at the same time, the methanol injector is controlled to inject methanol, so that the methanol is rapidly ignited and participates in the main combustion relying on the diesel flame. By using the second preset speed as a criterion, it can be clearly identified that the engine has entered a self-sustaining combustion state, avoiding misjudgment or premature switching of the injection mode. The diesel self-ignites at the end of compression to form a flame kernel, ensuring reliable ignition, and the methanol participates in combustion in large quantities under the ignition of the diesel flame, releasing additional energy to help the engine quickly transition from starting to stable operation, shortening the starting time. Since the diesel injection amount is relatively reduced, the methanol as a clean fuel provides more energy, which can reduce the soot emission during starting.

[0092] The above dual-fuel engine starting device includes a processor and a memory, and the first acquisition unit, the first control unit, the first determination unit, and the second control unit are all stored in the memory as program units, and the corresponding functions are realized by the processor executing the program units stored in the memory. The above modules are located in the same processor, or the modules are located in different processors in any combination.

[0093] The processor includes a core, and the core retrieves the corresponding program unit from the memory. The core can be set to one or more, and the core parameters are adjusted to at least solve the problem that the methanol fuel vapor pressure is low and the latent heat is large, making it difficult for the engine to start at low temperature.

[0094] The memory can include a non-persistent memory in a computer readable medium, a random access memory (RAM), and / or a non-volatile memory such as a read-only memory (ROM) or a flash memory (flash RAM), and the memory includes at least one memory chip.

[0095] The embodiment of the present application provides a computer readable storage medium, and the computer readable storage medium includes a stored program, wherein when the program runs, the device where the computer readable storage medium is located executes the dual-fuel engine starting method.

[0096] Specifically, the dual-fuel engine starting method includes:

[0097] In step S101, a plurality of temperature parameters are acquired in response to an engine starting instruction, and the minimum temperature parameter among all the temperature parameters is determined, wherein the temperature parameters include oil temperature, ambient temperature, coolant temperature, and intake air temperature.

[0098] Step S102, when the minimum temperature parameter is less than the preset temperature, controlling the diesel injector to inject a preset first injection amount of diesel into the engine cylinder;

[0099] Specifically, at the end of the compression stroke, the piston approaches the top dead center, and a preset first injection amount of diesel is injected, which has been determined during engine calibration, to ensure that sufficient compression heat source can be generated even under low temperature conditions.

[0100] Step S103, determining the speed change rate of the engine speed from the start to the first preset speed, and determining the second injection amount of diesel and the third injection amount of methanol according to the speed change rate;

[0101] Specifically, after the engine receives a start instruction, the crankshaft speed signal is continuously collected from the start of the engine, i.e. when the speed is 0, and the sampling frequency is generally in the millisecond level, for example, 1ms-5ms. When the engine speed rises from 0 to the first preset speed, the sampling is ended, thereby obtaining the speed curve of the starting stage, and the speed change rate is obtained by analyzing the steepness of the starting stage speed curve.

[0102] Step S104, controlling the diesel injector and the methanol injector to inject according to the second injection amount and the third injection amount, to start the engine.

[0103] Specifically, the diesel injection signal is triggered at the end of the compression stroke, when the piston approaches the top dead center, and the methanol can be injected synchronously with the diesel, or injected after the diesel combustion is established.

[0104] In an embodiment of the present application, after obtaining a plurality of temperature parameters in response to an engine start instruction, the method further comprises: when the minimum temperature parameter is greater than or equal to the preset temperature, controlling the methanol injector to inject a preset fourth injection amount of the methanol into the engine cylinder during the compression stroke of the engine, the fourth injection amount being determined based on the working condition of the engine when the minimum temperature parameter is greater than or equal to the preset temperature; controlling the diesel injector to inject the diesel when the piston reaches a preset position, so that the diesel ignites, and controlling the methanol injector to inject the methanol, the preset position being located before the top dead center of the piston.

[0105] In an embodiment of the present application, the method further comprises: in the case that the engine speed reaches the first preset speed, determining the rate of change of the engine speed, and in the case that the rate of change of the engine speed is greater than a preset rate of change of speed, obtaining a first difference between the rate of change of the engine speed and the preset rate of change of speed; determining the injection quantity adjustment coefficient corresponding to the first difference according to a preset mapping relationship between the first difference and the injection quantity adjustment coefficient, and obtaining a product of the injection quantity adjustment coefficient and the first difference, and determining the injection quantity of the methanol injector in the next compression stroke of the engine based on the product and the fourth injection quantity of the methanol.

[0106] In an embodiment of the present application, the method further comprises: in the case that the rate of change of the engine speed is less than or equal to the preset rate of change of speed, obtaining a second difference between the rate of change of the engine speed and the preset rate of change of speed; determining the diesel injection quantity correction value and the methanol injection quantity correction value in a preset first mapping relationship table based on the second difference, and determining the injection quantity of the methanol injector and the diesel injector in the next compression stroke of the engine according to the diesel injection quantity correction value and the methanol injection quantity correction value, the first mapping relationship table being a mapping relationship table of the second difference, the diesel injection quantity correction value and the methanol injection quantity correction value.

[0107] In an embodiment of the present application, the second injection quantity of diesel and the third injection quantity of methanol are determined according to the rate of change of the engine speed, comprising: determining the second injection quantity of diesel and the third injection quantity of methanol corresponding to the rate of change of the engine speed according to a preset second mapping relationship table, the second mapping relationship table being a mapping relationship table of the rate of change of the engine speed, diesel injection quantity and methanol injection quantity.

[0108] In an embodiment of the present application, in the case that the minimum temperature parameter is less than a preset temperature, before the diesel injector is controlled to inject a preset first injection quantity of diesel into the cylinder of the engine, the method further comprises: heating the engine oil to increase the oil temperature.

[0109] In an embodiment of the present application, the method further comprises: in the case that the engine speed is greater than or equal to a second preset speed, controlling the diesel injector to inject diesel in the case that the piston reaches a preset position to make the diesel ignite, and controlling the methanol injector to inject methanol to ignite the methanol, the second preset speed being used to determine that the engine completes starting.

[0110] The embodiment of the present application provides a dual-fuel engine starting system, and the device comprises a processor, a memory and a program stored in the memory and executable on the processor, and the processor implements at least the following steps when executing the program:

[0111] In step S101, a plurality of temperature parameters are acquired in response to an engine starting instruction, and the minimum temperature parameter in all the temperature parameters is determined, wherein the temperature parameters comprise an oil temperature, an ambient temperature, a coolant temperature and an intake air temperature.

[0112] In step S102, when the minimum temperature parameter is less than a preset temperature, the diesel injector is controlled to inject a preset first injection amount of diesel into the engine cylinder.

[0113] Specifically, the preset first injection amount of diesel is injected when the piston approaches the top dead center at the end of the compression stroke, and the first injection amount is determined during engine calibration, and can ensure that sufficient compression heat sources can be generated even under low-temperature conditions.

[0114] In step S103, a speed change rate of a process from engine static state to a first preset speed is determined, and the second injection amount of diesel and the third injection amount of methanol are determined according to the speed change rate.

[0115] Specifically, after the engine receives the starting instruction, the crankshaft speed signal is continuously collected from the engine static state, that is, when the speed is 0, and the sampling frequency is generally in the millisecond level, for example, 1ms-5ms. When the engine speed rises from 0 to the first preset speed, the sampling is ended, so that the speed curve in the starting stage is obtained, and the speed change rate is obtained by analyzing the steepness of the speed curve in the starting stage.

[0116] In step S104, the diesel injector and the methanol injector are controlled to inject according to the second injection amount and the third injection amount, so as to start the engine.

[0117] Specifically, the diesel injection signal is triggered at the end of the compression stroke when the piston approaches the top dead center, and the methanol can be injected synchronously with the diesel or injected supplementally after the diesel combustion is established.

[0118] The device herein can be a server, a PC, a PAD, a mobile phone or the like.

[0119] In an embodiment of the present application, after obtaining the plurality of temperature parameters in response to the engine start instruction, the method further comprises: in the case that the minimum temperature parameter is greater than or equal to the preset temperature, controlling the methanol injector to inject a preset fourth injection amount of the methanol into the engine cylinder in the compression stroke of the engine, the fourth injection amount being determined based on the working condition of the engine in the case that the minimum temperature parameter is greater than or equal to the preset temperature; and controlling the diesel injector to inject the diesel in the case that the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject the methanol, the preset position being located before the top dead center of the piston.

[0120] In an embodiment of the present application, after controlling the diesel injector to inject the diesel in the case that the piston reaches a preset position, so that the diesel is ignited, and controlling the methanol injector to inject the methanol, the method further comprises: in the case that the engine speed reaches the first preset speed, determining the speed change rate of the engine, and in the case that the speed change rate is greater than a preset speed change rate, obtaining a first difference value between the speed change rate and the preset speed change rate; determining the injection amount adjustment coefficient corresponding to the first difference value according to a preset mapping relationship between the first difference value and the injection amount adjustment coefficient, and obtaining a product of the injection amount adjustment coefficient and the first difference value, and determining the injection amount of the methanol injector in the next compression stroke of the engine based on the product and the fourth injection amount of the methanol, the first difference value and the injection amount adjustment coefficient corresponding to each other.

[0121] In an embodiment of the present application, the method further comprises: in the case that the speed change rate is less than or equal to the preset speed change rate, obtaining a second difference value between the speed change rate and the preset speed change rate; determining the diesel injection amount correction value and the methanol injection amount correction value in a preset first mapping relationship table based on the second difference value, and determining the injection amount of the methanol injector and the diesel injector in the next compression stroke of the engine according to the diesel injection amount correction value and the methanol injection amount correction value, the first mapping relationship table being a mapping relationship table of the second difference value, the diesel injection amount correction value and the methanol injection amount correction value.

[0122] In an embodiment of the present application, determining the second injection amount of the diesel and the third injection amount of the methanol according to the speed change rate comprises: determining the second injection amount of the diesel and the third injection amount of the methanol corresponding to the speed change rate according to a preset second mapping relationship table, the second mapping relationship table being a mapping relationship table of the speed change rate, the diesel injection amount and the methanol injection amount.

[0123] In one embodiment of the present application, when the minimum temperature parameter is less than the preset temperature, before the diesel injector is controlled to inject the preset first injection amount of diesel into the cylinder of the engine, the method further comprises: heating the oil of the engine to increase the oil temperature.

[0124] In one embodiment of the present application, the method further comprises: when the engine speed is greater than or equal to a second preset speed, controlling the diesel injector to inject diesel when the piston reaches the preset position so that the diesel ignites, and controlling the methanol injector to inject methanol so that the methanol ignites, the second preset speed being used to determine that the engine completes starting.

[0125] It is apparent that those skilled in the art should understand that the modules or steps of the present application described above can be realized by general computing devices, which can be centralized on a single computing device or distributed on a network composed of multiple computing devices, and can be realized by program codes executable by the computing devices, so that they can be stored in storage devices and executed by the computing devices, and in some cases, the steps shown or described can be executed in different order, or they can be manufactured into individual integrated circuit modules or a single integrated circuit module. Thus, the present application is not limited to any particular combination of hardware and software.

[0126] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROMs, optical storage devices, etc.) containing computer-usable program code.

[0127] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be realized by computer program instructions. These computer program instructions can be provided to a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to produce a machine, so that the instructions executed by the computer or other programmable data processing devices produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 The functions specified in one flow or multiple flows and / or blocks Figure 1 The devices that realize the functions specified in one block or multiple blocks.

[0128] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the multiple flows or blocks.

[0129] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the Figure 1 function specified in the flow or flows and / or blocks Figure 1 of the multiple flows or blocks.

[0130] In a typical configuration, a computing device includes one or more processors (CPUs), input / output interfaces, network interfaces, and memory.

[0131] The memory can include non-persistent memory and / or volatile memory, such as random access memory (RAM) and / or cache memory, non-volatile memory, such as read-only memory (ROM), EPROM, and / or flash memory. The memory is an example of computer-readable media.

[0132] Computer-readable media includes permanent and non-permanent, moveable and non- moveable media that can be implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disc read-only memory (CD-ROM), digital versatile discs (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information that can be accessed by a computing device. According to the definition herein, computer-readable media does not include transitory media, such as modulated data signals and carrier waves.

[0133] Any technical features in the above-described embodiments can be combined in any manner, and for the sake of brevity, not all possible combinations are described, however, it is to be understood that the application encompasses all possible combinations.

[0134] It should also be noted that the terms "comprising", "comprises", "including", "includes" or any other variation thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by "comprises a... " does not, without more constraints, exclude the presence of additional identical elements in the process, method, article, or apparatus that comprises the element.

[0135] From the above description, it can be seen that the above-described embodiments of the present application achieve the following technical effects:

[0136] 1) The dual-fuel engine starting method of the present application first acquires the oil temperature, ambient temperature, coolant temperature, and intake air temperature, and determines the minimum temperature parameter; when the minimum temperature parameter is less than the preset temperature, the diesel injector is controlled to inject a preset first injection amount of diesel into the engine cylinder; then the speed change rate of the engine speed from static to the first preset speed is determined, and the second injection amount of diesel and the third injection amount of methanol are determined according to the speed change rate; finally, the diesel injector and the methanol injector are controlled to inject according to the second injection amount and the third injection amount to start the engine. This scheme collects the oil temperature, ambient temperature, coolant temperature, and intake air temperature at the same time, and selects the minimum temperature parameter as the judgment basis, avoiding the misjudgment caused by a single temperature parameter, so as to more truly reflect the most unfavorable condition of the engine starting environment, and ensure that the starting strategy is more reliable under low temperature conditions. When the minimum temperature parameter is lower than the preset threshold, the ECU (Electronic Control Unit) controls the diesel injector to inject the first injection amount of diesel, and the diesel has high cetane number and good self-ignition performance, which can be more easily compression-ignited in low temperature environment, thereby ensuring smooth combustion and avoiding cold start failure. In the process of the engine from static to the first preset speed, the speed change rate is calculated, which directly reflects whether the engine combustion is sufficient. The higher the speed change rate, the stronger the combustion, and the diesel can be reduced and the methanol can be increased. The lower the speed change rate, the weaker the combustion, and the diesel amount needs to be increased to ensure ignition. Therefore, based on the speed change rate, the second injection amount of diesel and the third injection amount of methanol are determined, which can make the fuel injection more consistent with the actual working condition, avoiding energy deficiency or waste. When the second injection amount and the third injection amount are determined, the diesel injector and the methanol injector are controlled to inject at the same time. Diesel serves as the ignition source to ensure smooth ignition; methanol serves as the main fuel to participate in combustion and provide the main heat value, so that the engine can establish stable combustion in a short time, ensuring that the fuel can be compression-ignited in the cold start stage, and solving the problem that methanol fuel vapor pressure is low and latent heat is large, making it difficult for the engine to start at low temperature.

[0137] 2) The dual-fuel engine starting device of this application first acquires the engine oil temperature, ambient temperature, coolant temperature, and intake air temperature through a first acquisition unit and determines a minimum temperature parameter. When the minimum temperature parameter is less than a preset temperature, the first control unit controls the diesel injector to inject a preset first injection amount of diesel into the engine cylinder. Next, the first determination unit determines the rate of change of engine speed from standstill to reaching a first preset speed, and determines the second injection amount of diesel and the third injection amount of methanol based on the rate of change of speed. Finally, the second control unit simultaneously controls the diesel injector and the methanol injector to inject based on the second injection amount and the third injection amount to start the engine. This solution, by simultaneously acquiring engine oil temperature, ambient temperature, coolant temperature, and intake air temperature, and selecting the minimum temperature parameter as the judgment criterion, avoids misjudgment that may be caused by a single temperature parameter, thus more realistically reflecting the most unfavorable conditions of the engine starting environment and ensuring a more reliable starting strategy under low-temperature conditions. When the minimum temperature parameter is below a preset threshold, the ECU controls the diesel injectors to inject the first amount of diesel fuel. Diesel fuel has a high cetane number and good auto-ignition properties, making it easier to compress and ignite in low-temperature environments, thus ensuring successful combustion and preventing cold start failure. During the engine's journey from standstill to reaching the first preset speed, the rate of change of engine speed is calculated. This rate directly reflects the sufficiency of combustion; a large rate of increase indicates strong combustion, allowing for a reduction in diesel fuel and an increase in methanol. A small rate of increase indicates weak combustion, requiring an increase in diesel fuel to ensure ignition. Therefore, determining the second and third injection amounts of diesel fuel and methanol fuel based on the rate of change of engine speed ensures that fuel injection better matches actual operating conditions, avoiding insufficient or wasted energy. Once the second and third injection amounts are determined, both diesel and methanol injectors are controlled simultaneously. Diesel fuel acts as the ignition source, ensuring successful ignition; methanol, as the primary fuel, participates in combustion, providing the main calorific value. This allows the engine to establish stable combustion quickly, ensuring compressible combustion during the cold start phase and solving the problem of low vapor pressure and high latent heat of methanol fuel, which makes the engine difficult to start at low temperatures.

[0138] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for starting a dual-fuel engine, the engine comprising: A methanol injector (100) and a diesel injector (200), the methanol injector (100) being mounted to the intake manifold of the engine, and the diesel injector (200) being mounted to the cylinder head of the engine cylinder, characterized in that it comprises: Receive and respond to an engine start command, acquire multiple temperature parameters, and determine the minimum temperature parameter among all the temperature parameters, including oil temperature, ambient temperature, coolant temperature, and intake air temperature; When the minimum temperature parameter is less than the preset temperature, the diesel injector (200) is controlled to inject a preset first injection amount of diesel into the engine cylinder; Determine the rate of change of engine speed from standstill to reach a first preset speed, and determine the second injection quantity of diesel and the third injection quantity of methanol based on the rate of change of engine speed; The diesel injector (200) and the methanol injector (100) are simultaneously controlled to inject according to the second injection quantity and the third injection quantity to start the engine.

2. The method according to claim 1, characterized in that, After acquiring multiple temperature parameters in response to an engine start command, the method further includes: When the minimum temperature parameter is greater than or equal to the preset temperature, the methanol injector (100) is controlled to inject a preset fourth injection amount of methanol into the engine cylinder during the compression stroke of the engine. The fourth injection amount is determined based on the operating conditions of the engine when the minimum temperature parameter is greater than or equal to the preset temperature. When the piston reaches a preset position, the diesel injector (200) is controlled to inject diesel fuel to ignite the diesel fuel, and the methanol injector (100) is controlled to inject methanol. The preset position is located before the top dead center of the piston.

3. The method according to claim 2, characterized in that, After controlling the diesel injector (200) to inject diesel fuel when the piston reaches a preset position, thereby igniting the diesel fuel, and controlling the methanol injector (100) to inject methanol, the method further includes: When the engine speed reaches the first preset speed, the engine speed change rate is determined; when the speed change rate is greater than the preset speed change rate, a first difference between the speed change rate and the preset speed change rate is obtained. Based on the preset mapping relationship between the first difference and the injection quantity adjustment coefficient, the injection quantity adjustment coefficient corresponding to the first difference is determined, and the product of the injection quantity adjustment coefficient and the first difference is obtained. Based on the product and the fourth injection quantity of methanol, the injection quantity of the methanol injector (100) in the next compression stroke of the engine is determined, and the first difference corresponds one-to-one with the injection quantity adjustment coefficient.

4. The method according to claim 3, characterized in that, The method further includes: If the rotational speed change rate is less than or equal to the preset rotational speed change rate, a second difference between the rotational speed change rate and the preset rotational speed change rate is obtained; Based on the second difference, the diesel injection quantity correction value and the methanol injection quantity correction value are determined in the preset first mapping relationship table, and the injection quantity of the methanol injector (100) and the diesel injector (200) in the next compression stroke of the engine is determined according to the diesel injection quantity correction value and the methanol injection quantity correction value. The first mapping relationship table is a mapping relationship table between the second difference and the diesel injection quantity correction value and the methanol injection quantity correction value.

5. The method according to claim 1, characterized in that, Determining the second injection quantity of diesel and the third injection quantity of methanol based on the speed change rate includes: The second injection quantity of diesel and the third injection quantity of methanol corresponding to the speed change rate are determined according to a preset second mapping table. The second mapping table is a mapping table between the speed change rate and the diesel injection quantity and the methanol injection quantity.

6. The method according to claim 1, characterized in that, Before controlling the diesel injector (200) to inject a preset first injection amount of diesel into the engine cylinder when the minimum temperature parameter is less than a preset temperature, the method further includes: The engine oil is heated to increase its temperature.

7. The method according to any one of claims 1 to 6, characterized in that, The method further includes: When the engine speed is greater than or equal to the second preset speed, the diesel injector (200) is controlled to inject diesel fuel when the piston reaches the preset position so that the diesel fuel is ignited, and the methanol injector (100) is controlled to inject methanol so as to ignite the methanol. The second preset speed is used to determine that the engine has completed starting.

8. A dual-fuel engine starting device, the engine comprising: A methanol injector (100) and a diesel injector (200), the methanol injector (100) being mounted to the intake manifold of the engine, and the diesel injector (200) being mounted to the cylinder head of the engine cylinder, characterized in that it comprises: The acquisition unit is used to receive and respond to an engine start command, acquire multiple temperature parameters, and determine the minimum temperature parameter among all the temperature parameters, including engine oil temperature, ambient temperature, coolant temperature, and intake air temperature. The first control unit is used to control the diesel injector (200) to inject a preset first amount of diesel into the engine cylinder when the minimum temperature parameter is less than the preset temperature; The determining unit is used to determine the rate of change of engine speed from standstill to reach a first preset speed, and to determine the second injection quantity of diesel and the third injection quantity of methanol based on the rate of change of engine speed. The second control unit is configured to simultaneously control the diesel injector (200) and the methanol injector (100) to inject according to the second injection quantity and the third injection quantity, so as to start the engine.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the method according to any one of claims 1 to 7.

10. A dual-fuel engine starting system, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs comprising methods for performing any one of claims 1 to 7.

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