Engine, control method, electronic equipment, storage medium and vehicle

Abstract

The invention discloses an engine, a control method, electronic equipment, a storage medium and a vehicle. The control method comprises the steps that the working condition of the engine is obtained; obtaining the alcohol proportion in the engine; determining a fuel injection mode and an injection ratio based on the working condition and the alcohol ratio; controlling the engine to operate based on the fuel injection mode and the injection ratio; the injection mode is determined to be an in-cylinder direct injection mode; determining the injection mode as a double injection mode, and determining the injection ratio as a first injection ratio; the injection mode is determined to be a double injection mode, and the injection ratio is determined to be a second injection ratio; the injection mode is determined as a dual injection mode and the injection ratio is determined as a third injection ratio. The problems of difficult cold start, poor low-temperature operation performance, knocking, preignition and the like caused by independently adopting an air inlet channel injection mode can be reduced, and the problems of insufficient oil injection duration and high rail pressure corrosion caused by independently adopting an in-cylinder direct injection mode can be reduced.

Description

Technical Field

[0001] The present application relates to the field of engine technology, and in particular to an engine and control method, electronic equipment, storage medium, and vehicle. Background Art

[0002] An alcohol fuel engine is an engine that uses alcohol (such as methanol, ethanol or butanol) or a fuel blended with alcohol for energy. When using multiple alcohols and their mixed fuels at the same time, such an engine is also called a "flexible alcohol engine" or "elastic alcohol engine".

[0003] In the alcohol fuel engine in the related art, fuel injection generally adopts a fuel injection mode of intake port injection or direct injection into the cylinder. The intake port injection mode is conducive to large-flow injection of fuel with a high alcohol content, and the injection pressure is low, and the corrosive problem is not prominent. However, when the alcohol fuel engine adopts the intake port injection mode alone and uses fuel with a high alcohol content, it may have the problem of cold start difficulty, and it is necessary to add a preheating device or a special gasoline supply system for cold start. When using fuel with a low alcohol content, the problem of pre-ignition is prominent, the power at medium and low speeds is limited, and a smaller compression ratio needs to be used, which further weakens the engine efficiency.

[0004] The direct injection mode is beneficial to the cold start and low-temperature operation of alcohol flexible fuels. However, when the alcohol fuel engine adopts the direct injection mode alone, as the load increases, the required injection pressure and injection duration also continue to increase. The problem is that the injection cycle of direct injection is too long, and fuel can only be injected during the intake and compression strokes, which can easily cause problems such as wet wall and poor atomization. The injection duration is limited, and the rail pressure is high, and the corrosion problem is more serious. If the rail pressure is reduced, the injection time will be further extended, and the high-speed power output will be limited. It is necessary to develop larger flow and corrosion-resistant injectors and oil pumps, which leads to higher engine development costs. Summary of the invention

[0005] In view of the above, it is necessary to provide an engine and control method, electronic equipment, storage medium, and vehicle that can achieve flexible matching of injection control according to the composition characteristics of flexible alcohol fuel and operating conditions, thereby reducing the problems of cold start difficulty, poor low-temperature operating performance, detonation and pre-ignition that exist when using the intake port injection mode alone, as well as reducing the problems of insufficient injection duration and high rail pressure corrosion that exist when using the direct injection mode alone.

[0006] The first aspect of the present application provides an engine control method, comprising: obtaining the operating condition of the engine; obtaining the alcohol ratio in the engine; determining the fuel injection mode and injection ratio based on the operating condition and the alcohol ratio; and controlling the engine operation based on the fuel injection mode and the injection ratio; wherein the operating condition includes at least the load, temperature and start-stop state of the engine, the alcohol ratio is defined as the ratio of the content of flexible alcohol to the content of fuel, the injection mode includes the direct injection mode, the intake port injection mode and the dual injection mode, and the injection ratio is defined as the ratio of the fuel injection amount in the direct injection mode to the fuel injection amount in the intake port injection mode; determining the fuel injection mode and injection ratio based on the operating condition and the alcohol ratio includes: when the load is less than a predetermined load value, the temperature is less than a preset temperature value, or the start-stop state is started, determining the injection mode to be the direct injection mode Formula; when the load is greater than a predetermined load value and the alcohol ratio is close to a maximum value, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a first injection ratio, wherein the first injection ratio is defined as a ratio when the fuel injection amount in the direct injection mode is less than the fuel injection amount in the intake port injection mode; when the load is greater than a predetermined load value and the alcohol ratio is close to a minimum value, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a second injection ratio, wherein the second injection ratio is defined as a ratio when the fuel injection amount in the direct injection mode is greater than the fuel injection amount in the intake port injection mode; when the load is greater than a predetermined load value and the alcohol ratio is between a minimum value and a maximum value, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a third injection ratio, wherein the third injection ratio is between the first injection ratio and the second injection ratio.

[0007] In the control method of the present application, a predetermined load value can be used to define whether the load of the engine is in a low-load condition, and a preset temperature value can be used to define whether the temperature of the engine is in a low-temperature condition. At this time, the load is less than the predetermined load value, that is, the engine is in a low-load condition, and the temperature is less than the preset temperature value, that is, the engine is at a low temperature. When the start-stop state is start, the injection mode is determined to be the direct injection mode. The engine operates in the direct injection mode, and the fuel injection amount can be accurately controlled under any alcohol ratio and good fuel atomization and oil-gas mixing can be achieved, thereby achieving good starting performance, low-load fuel consumption and emission control.

[0008] In addition, when the load is greater than the predetermined load value and the alcohol ratio is close to the maximum value, at this time, the alcohol content in the engine's fuel is relatively high, and the engine operates in a medium or above load area. Therefore, it is determined that the injection mode to be adopted by the engine is the dual injection mode, and the injection ratio is determined to be the first injection ratio in which the fuel injection amount in the direct injection mode is less than the fuel injection amount in the intake port injection mode. In this case, the octane number of the fuel is higher, and the tendency to knock and pre-ignition is low. If the specific working area of ​​the engine is a large load, a larger proportion of the intake port injection mode is used, and a certain proportion of direct injection is used for fuel injection. Since the injection amount of direct injection in the cylinder is relatively small, the rail pressure of the direct injection mode can be maintained at a relatively low level, and the injection duration is relatively controllable, and the injection phase can be optimized according to fuel consumption and emissions.

[0009] In addition, when the load is greater than the predetermined load value and the alcohol ratio is close to the minimum value, at this time, the alcohol content in the engine's fuel is low, and the engine operates in a medium or higher load area. Therefore, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be the second injection ratio in which the fuel injection amount in the direct injection mode is greater than the fuel injection amount in the intake port injection mode. If the engine operates in an area with medium and low speeds, high loads, strong knock and prone to pre-ignition, the direct injection mode can be used, and a small proportion of intake port injection can be added or intake port injection can be not used based on subsequent calibrated performance, so as to solve the knock and pre-ignition problems and improve the engine's power output; if the engine operates at above medium load and in a medium and high speed area, a certain proportion of intake port injection can be added on the basis of the direct injection mode, so that the engine can achieve high power output under good conditions of direct injection injection duration and injection timing.

[0010] In addition, when the load is greater than the predetermined load value and the alcohol ratio is between the minimum value and the maximum value, at this time, the alcohol content in the engine's fuel is between low and high, and the engine operates in a medium and above load area, so the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be a third injection ratio between the first injection ratio and the second injection ratio, that is, the third injection ratio is a non-fixed value. In this case, if the specific working area of ​​the engine is a medium load, the appropriate third injection ratio can be determined through subsequent calibration optimization to reduce various problems caused by the use of direct injection in the cylinder alone or intake port injection alone.

[0011] In some embodiments, the operating conditions also include the engine speed; the fuel injection mode and injection ratio are determined based on the operating conditions and the alcohol ratio, including: when the load is greater than a predetermined load value, the alcohol ratio is close to a minimum value, and the speed is less than a predetermined speed, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a second injection ratio; when the load is greater than a predetermined load value, the alcohol ratio is close to a minimum value, and the speed is greater than a predetermined speed, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a fourth injection ratio; wherein the fourth injection ratio is between the second injection ratio and the third injection ratio.

[0012] In some embodiments, determining the injection ratio includes: if the alcohol ratio is close to a minimum value, using 1:0 as an initial injection ratio, and increasing the fuel injection amount in the intake port injection mode by a first preset increment to obtain multiple injection ratios; if the alcohol ratio is close to a maximum value, using 0:1 as an initial injection ratio, and increasing the fuel injection amount in the direct injection mode by a second preset increment to obtain multiple injection ratios; calibrating the operating conditions with the multiple injection ratios, wherein the calibration is related to the engine speed, injection time, and allowable rail pressure.

[0013] In some embodiments, determining the injection ratio also includes: calculating the median of the alcohol ratio, using the predicted value of the direct injection ratio under the median as the initial injection ratio, and increasing or decreasing the fuel injection amount in the direct injection mode by a third preset increment to obtain multiple injection ratios, wherein the median is equal to the sum of the maximum value and the minimum value divided by 2; calibrating the operating conditions and multiple injection ratios.

[0014] In some embodiments, determining the injection ratio also includes: obtaining an initial calibration curve based on a maximum value, a median value, and a minimum value; increasing or decreasing the content of the flexible alcohol by a fourth preset increment to obtain multiple alcohol ratios; and interpolating and optimizing the multiple alcohol ratios with the initial calibration curve to obtain a final calibration curve.

[0015] In some embodiments, the control method further includes: acquiring the oxygen content of the engine, and obtaining the air-fuel ratio of the engine based on the oxygen content; and re-acquiring the alcohol ratio in the engine based on the air-fuel ratio.

[0016] In some embodiments, controlling engine operation based on a fuel injection mode and an injection ratio includes: controlling at least one of the engine's injection pressure, injection amount, injection timing, intake and exhaust, or ignition combustion based on the fuel injection mode and the injection ratio.

[0017] In some embodiments, controlling engine operation based on a fuel injection mode and an injection ratio also includes: obtaining a model output torque and a target output torque of the engine, wherein the model output torque is defined as the actual output torque of the engine based on the fuel injection mode and the injection ratio, and the target output torque is defined as the theoretical output torque of the engine based on the fuel injection mode and the injection ratio; if the model output torque is less than the target output torque, then re-controlling at least one of the engine's injection pressure, injection amount, injection timing, intake and exhaust, or ignition combustion based on the fuel injection mode and the injection ratio.

[0018] The second aspect of the present application provides an engine, including a control device, an engine body, an intake system, a fuel supply system and an exhaust after-treatment system; the control device is connected to the engine body, the intake system, the fuel supply system and the exhaust after-treatment system, and is used to execute the control method of any embodiment of the first aspect of the present application to control the engine; the fuel supply system includes a first sensor for detecting the alcohol content; the exhaust after-treatment system includes a second sensor for detecting the oxygen content.

[0019] A third aspect of the present application provides an electronic device, the electronic device comprising a memory and a processor, the memory storing a computer program, and the processor implementing the engine control method of any embodiment of the first aspect of the present application when executing the computer program.

[0020] A fourth aspect of the present application provides a computer-readable storage medium, the storage medium storing a computer program, and when the computer program is executed by a processor, the engine control method of any embodiment of the first aspect of the present application is implemented.

[0021] A fifth aspect of the present application provides a vehicle, the vehicle includes an engine, the engine includes a control device, and the control device is used to execute the engine control method of any embodiment of the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of the engine control method according to the embodiment of the present application.

[0023] Figure 2 It is a flowchart of the calibration process of step S300 of an embodiment of the present application.

[0024] Figure 3 It is a flowchart of the calibration process of another embodiment of step S300 of the embodiment of the present application.

[0025] Figure 4 It is a flowchart of the calibration process of another embodiment of step S300 of the embodiment of the present application.

[0026] Figure 5 It is a sub-flowchart of step S400 of an embodiment of the present application.

[0027] Figure 6 It is a flow chart of another embodiment of the engine control method of the embodiment of the present application.

[0028] Figure 7 It is a structural block diagram of the engine of an embodiment of the present application.

[0029] Main component symbols 1. Engine; 11. Control device; 12. Engine body; 13. Intake system; 14. Fuel supply system; 15. Exhaust after-treatment system; 141. In-cylinder direct injection subsystem; 142. Intake port injection subsystem.

[0030] The following specific implementation mode will further illustrate the present application in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION In the description of the embodiments of the present application, words such as "exemplary", "or", "for example" and the like are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary", "or", "for example" and the like is intended to present related concepts in a specific mode.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field in this application. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. It should be understood that, unless otherwise specified in this application, " / " means or. For example, A / B can represent A or B. "And / or" in this application is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. "At least one" means one or more. "Multiple" means two or more than two. For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c, a, b and c seven situations.

[0033] It should also be noted that the terms "first" and "second" in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. The method disclosed in the embodiments of this application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0034] Under the global trend of low carbonization, low carbon fuels such as ethanol and methanol are widely praised in many regions. At present, there are pure gasoline, ethanol, methanol, other different alcohols and flexible alcohol fuels on the market. Among them, flexible alcohol fuel is also called elastic alcohol fuel, which is obtained by mixing ethanol, methanol or other different alcohols with gasoline. Alcohol fuel engine, that is, an engine that uses alcohol or fuels mixed with alcohol for energy driving. When using multiple alcohols and their mixed fuels at the same time, such engines are also called "flexible alcohol engines" or "flexible alcohol engines".

[0035] The fuel characteristics of different alcohol ratios vary greatly, with different advantages and disadvantages. The engine performance under different working conditions will also vary greatly. Specifically, when the alcohol content in alcohol fuel is low, the octane number is low, the fuel anti-knock performance is poor, and the pre-ignition tendency is strong, which will affect the engine's low-speed power output. At the same time, it is not suitable for improving the cycle thermal efficiency through a higher compression ratio. The advantage of low alcohol content in alcohol fuel is that the corrosiveness is relatively small, which can reduce the requirements for corrosion-resistant materials, so that the engine can use a larger rail pressure. Another advantage is better cold start performance. When the alcohol content ratio in alcohol fuel is high, the advantages are high anti-knock performance and low pre-ignition tendency, which can make the engine easy to obtain high power and good combustion phase at low and medium speeds, but there are problems such as low fuel calorific value, large injection volume, long injection duration, easy wall wetting, oil dilution, deterioration of combustion emissions, poor fuel volatility, and obvious low temperature, which can easily cause cold start difficulties. In addition, when the alcohol content ratio is high, its corrosiveness is strong, and the corrosion problem will be more prominent when the engine uses high rail pressure. Therefore, for flexible alcohol fuel engines that use any blending ratio, it is difficult to ensure that the values ​​remain reasonable and feasible when burning fuels of all alcohol ratios, and to maintain a high level of performance output. Therefore, targeted strengthening or improvement measures are needed to address the corresponding issues.

[0036] In the alcohol fuel engine in the related art, fuel injection generally adopts a fuel injection mode of intake port injection or direct injection in the cylinder. The intake port injection mode can inject fuel throughout the entire cycle, and the available injection duration is long, which is conducive to large-flow injection of fuel with a large alcohol content, and the injection pressure is low, and the corrosion problem is not prominent. However, when the alcohol fuel engine adopts the intake port injection mode alone and uses a fuel with a high alcohol content, since the fuel mixes with the air in the intake duct, part of the fuel is adsorbed on the wall to form an oil film, and the oil and gas are difficult to fully mix. When running in cold start and low temperature conditions, because the high alcohol ratio fuel is difficult to evaporate, more fuel will be first adsorbed on the airway or valve, and then the effective oil-gas mixture that can enter the cylinder in time will be reduced, so the fuel quantity control accuracy is low, which is easy to cause cold start difficulties, increased fuel consumption, and poor emissions. At the same time, when the engine is working in the medium and low speed high load area, due to the large amount of fuel injection, the oil and gas mixture is more uneven, and there is no evaporation and heat absorption process after entering the cylinder. Therefore, the compression stroke heat load is high, which is prone to knock and pre-ignition, greatly limiting the engine's medium and low speed power output. In other words, the intake port injection mode has the problem of cold start difficulty, and it is necessary to add a preheating device or a special gasoline supply system for cold start. When using fuel with low alcohol content, the pre-ignition problem is prominent, the medium and low speed power is limited, and a smaller compression ratio needs to be used, further weakening the engine efficiency.

[0037] In the direct injection mode, the fuel is directly injected into the cylinder. Through the control of multiple parameters such as injection pressure, injection beam shape, injection angle, injection time, etc., the oil-gas mixing effect and the control accuracy of the fuel amount are greatly improved compared with the intake port injection, which can be beneficial to the cold start and low-temperature operation of alcohol flexible fuels, and can achieve good cold start performance and low-temperature operating economy and emissions without the need for additional heating devices. In addition, since the evaporation heat absorption of the fuel injected into the cylinder can effectively reduce the cylinder temperature at the end of compression, the knock and pre-ignition of the engine at medium and low speeds and high loads can be improved. In this case, the engine can use a larger compression ratio and a higher degree of boost to maintain high power output. However, when the alcohol fuel engine adopts the direct injection mode alone, as the load increases, the required injection pressure and injection duration are also continuously increased. The problem is that the injection cycle of direct injection in the cylinder is too long, and it can only be injected during the intake and compression strokes, which is easy to cause problems such as wet wall and poor atomization. The injection duration is limited, and the rail pressure is high, and the corrosion problem is more serious, so it is necessary to develop special corrosion-resistant materials. If the rail pressure is reduced, the injection time will be further prolonged, which may easily lead to limited high-speed power output of the engine. It is necessary to develop larger flow, corrosion-resistant injectors and oil pumps, which may easily lead to higher engine development costs.

[0038] In the related art, in order to solve the problems caused by using the direct injection mode or the intake manifold injection mode alone, there is also a dual injection mode that combines the direct injection mode and the intake manifold injection mode. However, this mode can only solve part of the above problems, such as pre-ignition or cold start difficulties. Other problems that seriously affect engine performance, such as corrosiveness and output efficiency, require the development of auxiliary devices with extremely complex structures, which is not conducive to reducing the development cost of the engine.

[0039] In summary, it is difficult to deal with all the above-mentioned prominent problems by using the direct injection mode, the intake port injection mode or the existing dual injection mode alone.

[0040] To this end, the embodiments of the present application provide an engine and control method, electronic equipment, storage medium, and vehicle, which can realize flexible matching of injection control according to the composition characteristics of flexible alcohol fuel and operating conditions, thereby reducing the cold start difficulty, poor low-temperature operating performance, knock and pre-ignition problems existing in the intake port injection mode alone, and reducing the problems of insufficient injection duration and high rail pressure corrosion existing in the direct injection mode alone. Some embodiments will be described below in conjunction with the accompanying drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0041] Figure 1 It is a flow chart of the engine control method according to the embodiment of the present application.

[0042] See also Figure 1 The present application embodiment first provides a control method for an engine, which is hereinafter referred to as "control method" or "method" for ease of description. The control method involved in the present application embodiment may include: Step S100: Acquire the operating condition of the engine.

[0043] The engine operating condition includes at least the engine load, temperature, and start / stop state. Obtaining the engine operating condition may be obtaining the current operating condition and target operating condition of the engine. The current operating condition may be used to determine the current operating state of the engine, such as whether a large load is being dragged or whether the temperature reaches the operating temperature. The target operating condition may be used to compare the current operating condition to determine whether the engine control meets the requirements, such as whether the engine output torque reaches the target output torque.

[0044] In some embodiments, the operating conditions of the engine may also include speed, torque or pressure, etc.

[0045] In some embodiments, the current operating condition and the target operating condition may be determined by current engine speed, accelerator pedal position, accelerator pedal change rate, vehicle speed, intake air temperature, intake air pressure, water temperature, oil temperature or intake air temperature, etc. In other embodiments, the current operating condition and the target operating condition may also be determined by environmental information.

[0046] See also Figure 1 The control method involved in the embodiment of the present application may also include: Step S200: Obtaining the alcohol ratio in the engine.

[0047] The alcohol ratio is defined as the ratio of the content of flexible alcohol to the content of fuel. The alcohol ratio can be used to clarify the composition characteristics of the fuel. Specifically, the content of methanol or ethanol in the fuel is measured in real time by the alcohol content sensor, so as to calculate the ratio of fuel alcohol to gasoline, and thus calculate the density, calorific value and estimated octane number of the fuel.

[0048] The flexible alcohols in the embodiments of the present application may include, but are not limited to, alcohol-based compounds such as methanol, ethanol or butanol.

[0049] In the embodiment of the present application, the content of flexible alcohol can be detected by an alcohol content sensor disposed in the fuel supply system. Specifically, the content of flexible alcohol can be detected by an alcohol content sensor disposed at the inlet of the high-pressure fuel pump. In this case, the alcohol content sensor is disposed at the inlet of the high-pressure fuel pump instead of in the fuel tank, so that the alcohol content sensor is closer to the fuel injection system, and the flexible alcohol content obtained is closer to the fuel characteristics injected into the cylinder, thereby improving the accuracy of control.

[0050] See also Figure 1 The control method involved in the embodiment of the present application may also include: Step S300: Determine the fuel injection mode and injection ratio based on the operating conditions and the alcohol ratio.

[0051] Among them, the injection mode includes direct injection mode, intake port injection mode and dual injection mode, and the injection ratio is defined as the ratio of the fuel injection amount in the direct injection mode to the fuel injection amount in the intake port injection mode.

[0052] Step S300 of the embodiment of the present application may specifically be: When the load is less than a predetermined load value, the temperature is less than a preset temperature value, or the start-stop state is start, the injection mode is determined to be the cylinder direct injection mode. In this case, the predetermined load value can be used as a condition to define whether the load of the engine is in a low-load condition, and the preset temperature value can be used as a condition to define whether the temperature of the engine is in a low-temperature condition. At this time, the load is less than the predetermined load value, that is, the engine is in a low-load condition, the temperature is less than the preset temperature value, that is, the engine is in a low-temperature condition, and the start-stop state is start, thereby determining the injection mode as the cylinder direct injection mode. The engine is operated in the cylinder direct injection mode, and the fuel injection amount can be accurately controlled under any alcohol ratio and good fuel atomization and oil-gas mixing can be achieved, thereby achieving good starting performance, low-load fuel consumption and emission control.

[0053] When the load is greater than a predetermined load value and the alcohol ratio is close to a maximum value, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a first injection ratio, wherein the first injection ratio is defined as a ratio when the fuel injection amount in the direct injection mode is less than the fuel injection amount in the intake port injection mode. In this case, the predetermined load value can be used as a definition of whether the engine load is in a low-load condition. At this time, when the load is greater than the predetermined load value and the alcohol ratio is close to the maximum value, that is, the alcohol content in the engine fuel is relatively high, and the engine operates in a medium or above load area. Therefore, it is determined that the injection mode to be adopted by the engine is the dual injection mode, and the injection ratio is determined to be the first injection ratio in which the fuel injection amount in the direct injection mode is less than the fuel injection amount in the intake port injection mode. In this case, the octane number of the fuel is higher, and the tendency of knock and pre-ignition is low. If the specific working area of ​​the engine is a large load, a larger proportion of the intake port injection mode is used, and a certain proportion of direct injection is used for fuel injection. Since the injection amount of direct injection in the cylinder is relatively small, the rail pressure of the direct injection mode can be maintained at a relatively low level, and the injection duration is relatively controllable, and the injection phase can be optimized according to fuel consumption and emissions.

[0054] When the load is greater than the predetermined load value and the alcohol ratio is close to the minimum value, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be the second injection ratio, wherein the second injection ratio is defined as the ratio when the fuel injection amount in the direct injection mode is greater than the fuel injection amount in the intake port injection mode. In this case, the predetermined load value can be used as a definition of whether the engine load is in a low-load condition. At this time, when the load is greater than the predetermined load value and the alcohol ratio is close to the minimum value, that is, the alcohol content in the engine fuel is low, and the engine operates in a medium or above load area, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be the second injection ratio in which the fuel injection amount in the direct injection mode is greater than the fuel injection amount in the intake port injection mode. If the engine operates in a medium-low speed, high load, strong knock and prone to pre-ignition area, the direct injection mode can be used, and a small proportion of intake port injection can be added or intake port injection can be not used based on subsequent calibration performance, so as to solve the knock and pre-ignition problems and improve the engine's power output; if the engine operates above medium load and in a medium-high speed area, a certain proportion of intake port injection can be added on the basis of the direct injection mode, thereby enabling the engine to achieve high power output under good conditions of direct injection injection duration and injection timing.

[0055] When the load is greater than the predetermined load value and the alcohol ratio is between the minimum value and the maximum value, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be the third injection ratio, wherein the third injection ratio is between the first injection ratio and the second injection ratio. In this case, the predetermined load value can be used as a condition to define whether the load of the engine is in a low load condition. At this time, when the load is greater than the predetermined load value and the alcohol ratio is between the minimum value and the maximum value, that is, the alcohol content in the fuel of the engine is between low and high, and the engine works in a load area of ​​medium and above intensity, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be the third injection ratio between the first injection ratio and the second injection ratio, that is, the third injection ratio is a non-fixed value. In this case, if the specific working area of ​​the engine is medium load, the appropriate third injection ratio can be determined through subsequent calibration optimization to reduce various problems caused by the use of direct injection in the cylinder alone or intake port injection alone.

[0056] Optionally, when the load is greater than a predetermined load value, the alcohol ratio is close to a minimum value, and the speed is less than a predetermined speed, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a second injection ratio. In this case, the predetermined load value can be used to define whether the load of the engine is in a light load condition, and the predetermined speed can be used to define whether the speed of the engine is at a medium speed or above. At this time, when the load is greater than the predetermined load value, the alcohol ratio is close to a minimum value, and the speed is less than the predetermined speed, that is, the alcohol content in the fuel of the engine is low, the engine is operating in a medium or above load area, and the engine is operating in a medium and low speed state. In other words, the engine is in a medium and low speed, high load area with strong knock and easy pre-ignition, so the injection mode can be determined to be a dual injection mode, and the injection ratio can be determined to be the second injection ratio, thereby solving the knock and pre-ignition problems and improving the power output of the engine.

[0057] Optionally, when the load is greater than a predetermined load value, the alcohol ratio is close to a minimum value, and the speed is greater than a predetermined speed, the injection mode is determined to be a dual injection mode, and the injection ratio is determined to be a fourth injection ratio. The fourth injection ratio is between the second injection ratio and the third injection ratio. In this case, the predetermined load value can be used to define whether the load of the engine is in a light load condition, and the predetermined speed can be used to define whether the speed of the engine is at a medium speed or above. At this time, when the load is greater than the predetermined load value, the alcohol ratio is close to a minimum value, and the speed is greater than the predetermined speed, that is, the alcohol content in the fuel of the engine is low, the engine works in a load area of ​​medium or above intensity, and the engine works in a medium-high speed state, so the injection mode can be determined to be a dual injection mode, and the injection ratio is determined to be a fourth injection ratio. The fourth injection ratio adds more intake port injection on the basis of the second injection ratio, thereby enabling the engine to achieve high power output under good conditions of direct injection injection duration and injection timing in the cylinder.

[0058] In some embodiments, the determined injection mode may be stored in an electronic control unit (ECU) of the engine.

[0059] In some embodiments, the preferred injection mode control map can be calibrated based on the operating conditions and fuel composition characteristics, which can specifically include selecting a direct injection only injection mode, an intake port only injection mode, and dual injection modes in different proportions.

[0060] In some embodiments, the target intake volume, target air-fuel ratio and target fuel injection volume of the engine may be further determined in step S300. The target intake volume is the amount of fresh air required to generate the target torque under the engine state and environmental conditions, the target air-fuel ratio is the ratio of air to fuel required for combustion and enrichment protection, and the target fuel injection volume is the amount of direct injection and port injection required for combustion and enrichment protection.

[0061] In some embodiments, the target intake air amount, the target air-fuel ratio and the target fuel injection amount can be calculated and calibrated based on the fuel-air combustion reaction formula, fuel component characteristics and operating conditions.

[0062] In the embodiment of the present application, in the direct injection mode, the fuel injection pressure can be flexibly controlled according to the fuel composition characteristics, operating conditions and the proportion of direct injection in the cylinder. When the proportion of alcohol content in the fuel is low, the fuel corrosiveness is low, and a higher fuel injection pressure is used to obtain better combustion and emission performance; when the proportion of alcohol content in the fuel is high, the fuel injection pressure can be appropriately reduced to reduce corrosiveness. For intake port injection, a fixed lower pressure that meets the injection pressure is uniformly used.

[0063] Figure 2 It is a flowchart of the calibration process of step S300 of an embodiment of the present application.

[0064] In some embodiments, as described above, the embodiments of the present application can control the map of the injection mode based on the calibration of the operating conditions and fuel composition characteristics. Figure 2 The calibration process of step S300 may specifically include: Step S310: If the alcohol ratio is close to the minimum value, 1:0 is used as the initial injection ratio, and the fuel injection amount in the intake port injection mode is increased by a first preset increment to obtain multiple injection ratios.

[0065] Among them, 1 and 0 refer to percentages, 1 specifically refers to 100%, and 0 specifically refers to 0% or not used. The first preset increment is also called "step size", and the first preset increment can be 0.1, 0.2, 0.3 or more.

[0066] When the alcohol ratio is close to the minimum value, that is, the alcohol content in the engine's fuel is low, the octane number in the fuel is low, the fuel anti-knock performance is poor, and the pre-ignition tendency is strong, which will affect the engine's low-speed power output, and it is not suitable to use a higher compression ratio to improve the cycle thermal efficiency. Therefore, 1:0 is used as the initial injection ratio at this time, that is, the engine is mainly in direct injection mode at this time, and the fuel injection amount in the intake port injection mode is increased by the first preset increment to obtain multiple injection ratios. For example, the first preset increment is 0.2, and the obtained injection ratios may include 1:0, 0.8:0.2, 0.6:0.4 and more. The process can be expressed by the formula (1-x): x, where x is the ratio of the intake port injection mode.

[0067] In some embodiments, the fuel injection amount in the direct injection mode may also be reduced by a first preset increment in step S310 to obtain multiple injection ratios. That is, in the embodiment of the present application, the fuel injection amount in the port injection mode may be inversely correlated with the fuel injection amount in the direct injection mode, for example, if the fuel injection amount in the port injection mode increases, the fuel injection amount in the direct injection mode decreases.

[0068] In some embodiments, the obtained injection ratio may be used as the second injection ratio and the fourth injection ratio according to the comprehensive performance of the engine.

[0069] See also Figure 2 The calibration process of step S300 may further include: Step S320: If the alcohol ratio is close to the maximum value, 0:1 is used as the initial injection ratio, and the fuel injection amount in the direct injection mode is increased by a second preset increment to obtain multiple injection ratios.

[0070] Among them, 1 and 0 refer to percentages, 1 specifically refers to 100%, and 0 specifically refers to 0% or not used. The second preset increment can be the same as the first preset increment, that is, the second preset increment can be 0.1, 0.2, 0.3 or more.

[0071] When the alcohol ratio is close to the maximum value, that is, the alcohol content in the engine fuel is high, the engine's anti-knock performance is high, the pre-ignition tendency is low, and the engine can easily obtain medium and low speed high power and good combustion phase, but there are problems such as low fuel calorific value, large injection volume, long injection duration, easy wall wetting, oil dilution, deterioration of combustion emissions, poor fuel volatility and obvious low temperature, which can easily cause cold start difficulties. In addition, when the alcohol content ratio is high, it is highly corrosive, and the engine will be more corrosive when using high rail pressure. Therefore, 0:1 is used as the initial injection ratio at this time, that is, the engine is mainly in the intake port injection mode at this time, and the fuel injection amount in the direct injection mode in the cylinder is increased by the second preset increment to obtain multiple injection ratios. For example, the second preset increment is 0.2, and the obtained injection ratios may include 0:1, 0.2:0.8, 0.4:0.6 and more. The process can be expressed by the formula x: (1-x), where x is the ratio of the intake port injection mode.

[0072] In some embodiments, the fuel injection amount in the port injection mode may also be reduced by a second preset increment in step S320 to obtain multiple injection ratios. That is, in the embodiment of the present application, the fuel injection amount in the port injection mode may be inversely correlated with the fuel injection amount in the direct injection mode, for example, if the fuel injection amount in the port injection mode increases, the fuel injection amount in the direct injection mode decreases.

[0073] In some embodiments, the obtained injection ratio may be used as the first injection ratio according to the comprehensive performance of the engine.

[0074] In addition, in the embodiment of the present application, the order of step S310 and step S320 may not be limited, that is, step S310 may also be executed after step S320.

[0075] See also Figure 2 The calibration process of step S300 may further include: Step S330: Calibrate the operating conditions and multiple injection ratios.

[0076] Among them, the calibration is related to the engine speed, injection time and allowable rail pressure.

[0077] Figure 3 is a flowchart of the calibration process of another embodiment of step S300 of the embodiment of the present application. Figure 2 and Figure 3 The difference between the embodiments is that step S300 may further include: Step S321: Calculate the median of the alcohol ratio, use the predicted value of the direct injection ratio under the median as the initial injection ratio, and increase or decrease the fuel injection amount in the direct injection mode by a third preset increment to obtain multiple injection ratios.

[0078] In practice, when the above-mentioned problem of alcohol ratio is not obvious, it can be considered that the alcohol ratio is between the maximum value and the minimum value. At this time, it is necessary to calculate and predict the median value of the alcohol ratio. Among them, the median value of the alcohol ratio is equal to the sum of the maximum value and the minimum value of the alcohol ratio divided by 2. The direct injection ratio prediction value can be between 0 and 0.5 or between 0.5 and 1. If the direct injection ratio prediction value is between 0 and 0.5, the fuel injection amount in the direct injection mode is increased by the third preset increment. If the direct injection ratio prediction value is between 0.5 and 1, the fuel injection amount in the direct injection mode is reduced by the third preset increment. The third preset increment can be the same as the first preset increment.

[0079] In some embodiments, the fuel injection amount in the port injection mode may also be increased or decreased by a third preset increment in step S330 to obtain multiple injection ratios. That is, in the embodiment of the present application, the fuel injection amount in the port injection mode may be inversely correlated with the fuel injection amount in the direct injection mode, for example, if the fuel injection amount in the port injection mode increases, the fuel injection amount in the direct injection mode decreases.

[0080] In some embodiments, the obtained injection ratio may be used as the third injection ratio according to the comprehensive performance of the engine.

[0081] Figure 4 is a flowchart of a calibration process of another embodiment of step S300 of the present application. Figure 2 , Figure 3 and Figure 4 The difference between the embodiments is that step S300 may further include: Step S340: obtaining an initial calibration curve based on the maximum value, the median value, and the minimum value.

[0082] Step S341: increasing or decreasing the content of the flexible alcohol by a fourth preset increment to obtain a plurality of alcohol ratios.

[0083] Step S342: interpolating and optimizing the multiple alcohol ratios with the initial calibration curve to obtain a final calibration curve.

[0084] The fourth preset increment may be determined according to comprehensive performance of the engine.

[0085] Therefore, a calibration curve can be generated through steps S340 to S342 to improve the calibration accuracy.

[0086] See also Figure 1 The control method involved in the embodiment of the present application may also include: Step S400: Controlling the engine operation based on the fuel injection mode and injection ratio.

[0087] Figure 5 is a sub-flow chart of step S400 of the embodiment of the present application. In other embodiments, please refer to Figure 5 , step S400 may include: Step S401: Control at least one of the injection pressure, injection amount, injection timing, intake and exhaust, or ignition combustion of the engine based on the fuel injection mode and injection ratio.

[0088] Step S402: Obtain the model output torque and target output torque of the engine.

[0089] The model output torque is defined as the actual output torque of the engine based on the fuel injection mode and injection ratio, and the target output torque is defined as the theoretical output torque of the engine based on the fuel injection mode and injection ratio.

[0090] Step S403: If the model output torque is less than the target output torque, at least one of the injection pressure, injection amount, injection timing, intake and exhaust or ignition combustion of the engine is re-controlled based on the fuel injection mode and injection ratio.

[0091] In this way, the engine can be controlled in a closed loop to improve the control accuracy.

[0092] Figure 6 It is a flow chart of another embodiment of the engine control method of the embodiment of the present application.

[0093] See also Figure 6 In some embodiments, the control method may further include: Step S500: Acquire the oxygen content of the engine, and obtain the air-fuel ratio of the engine based on the oxygen content.

[0094] After executing step S500, the alcohol ratio in the engine may be re-acquired based on the air-fuel ratio, that is, step S200 may be re-executed.

[0095] This allows closed-loop confirmation of the alcohol ratio in the engine, improving control accuracy.

[0096] In addition, in the control method of the present application, compared with the single injection mode, a dual injection mode is added, and the flow range of the injector does not need to be greatly increased under the existing mature models, while taking into account the working conditions with small flow requirements, reducing the development cost of the injector. In addition, in the control method involved in the embodiment of the present application, the appropriate reduction of the rail pressure can reduce the development cost of corrosion protection optimization. In addition, the control method involved in the embodiment of the present application can reduce the additional mechanism set for the startup optimization of the single injection mode.

[0097] Figure 7 It is a structural block diagram of the engine of an embodiment of the present application.

[0098] See also Figure 7 The embodiment of the present application also provides an engine 1, which may be an alcohol fuel engine, which may include a control device 11, an engine body 12, an intake system 13, a fuel supply system 14 and an exhaust after-treatment system 15; the control device 11 is connected to the engine body 12, the intake system 13, the fuel supply system 14 and the exhaust after-treatment system 15, and the control device 11 is used to execute the control method of any of the above embodiments of the present application to control the engine 1; the fuel supply system 14 includes a first sensor for detecting the alcohol content; the exhaust after-treatment system 15 includes a second sensor for detecting the oxygen content.

[0099] In some embodiments, the intake system 13 may include an air filter, a supercharger, an intake intercooler, an intake manifold, and a plurality of intake manifolds.

[0100] In some embodiments, the fuel supply system 14 may include an in-cylinder direct injection subsystem 141 and an intake port injection subsystem 142. The in-cylinder direct injection subsystem 141 may include a high-pressure fuel injector, a high-pressure fuel rail, a high-pressure fuel pump, and a connecting pipeline. The intake port injection subsystem 142 may include a low-pressure fuel injector, a low-pressure fuel rail, a low-pressure fuel pump, and a connecting pipeline. In other embodiments, the intake port injection subsystem 142 may also include a pressure reducing device. In other embodiments, the low-pressure fuel pump may not be provided, and the fuel of the intake port injection subsystem 142 may be output as low-pressure fuel through the high-pressure fuel pump of the in-cylinder direct injection subsystem 141 and then through the pressure reducing device.

[0101] In an embodiment of the present application, the fuel supply system 14 can use flexible alcohol fuels with different alcohol contents, and provide sufficient fresh air through the intake system 13 to be fully mixed with the fuel in the cylinder or in the intake manifold of each cylinder. The fuel directly injected into the cylinder is directly injected into the cylinder, and the mixture formed by the intake port injection in the intake manifold enters the cylinder for further full mixing or further full mixing with the direct injection fuel into the cylinder. After the mixed gas is ignited and burned in the combustion chamber, it enters the exhaust system after passing through the exhaust pipe and the supercharger turbine to do work.

[0102] In some embodiments, the exhaust aftertreatment system 15 may further include an exhaust pipe, and the second sensor may be disposed in the exhaust pipe.

[0103] In the cylinder direct injection subsystem 141, the fuel passes through the high-pressure oil pump and enters the high-pressure oil rail, and is directly sprayed into the cylinder from the high-pressure injector arranged on the top of the engine body 12 or on the intake side, and is mixed with the fresh air entering through the intake manifold or the oil-gas mixture injected from the intake duct to form an oil-gas mixture, which is ignited and burned in the engine combustion chamber. The burned mixture enters the exhaust after-treatment system 15 after work is performed by the supercharger, and is finally discharged into the atmosphere.

[0104] In the intake port injection subsystem 142, the fuel passes through a low-pressure oil pump or first passes through a high-pressure oil pump and then passes through a pressure reducing device, and enters a low-pressure oil pipe arranged on the intake manifold, and is sprayed into the intake manifold of each cylinder by a low-pressure injector, and is mixed with the fresh air that has been pressurized by the supercharger and cooled by the intercooler in the intake manifold to form an oil-gas mixture, which enters the cylinder when the intake valve is opened, participates in the next step of mixing or is directly ignited and burned in the engine combustion chamber, and the burned mixture enters the exhaust after-treatment system 15 after the supercharger does work, and is finally discharged into the atmosphere.

[0105] In some embodiments, the control device 11 may be an ECU of a vehicle. The ECU may control the fuel pressure, injection amount or injection timing of the in-cylinder direct injection subsystem 141 and the intake port injection subsystem 142, and perform operating conditions and closed-loop control of the dual injection system according to the alcohol content sensor signal arranged in the fuel supply system 14, the oxygen sensor signal in the exhaust aftertreatment system 15, and the operating conditions, and achieve optimal control of the engine through matching control of the dual injection mode parameters with other parameters.

[0106] An embodiment of the present application also provides an electronic device, which includes a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the engine control method of any of the above embodiments of the present application is implemented.

[0107] An embodiment of the present application further provides a computer-readable storage medium, the storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the engine control method of any of the above embodiments of the present application.

[0108] An embodiment of the present application also provides a vehicle, the vehicle includes an engine, the engine includes a control device, and the control device is used to execute the engine control method of any of the above embodiments of the present application.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and are not intended to limit it. Although the present application has been described in detail with reference to the preferred embodiments, a person of ordinary skill in the art should understand that the technical solution of the present application may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application.

Claims

1. A method for controlling an engine, characterized in that: include: Obtain the engine's operating conditions; obtaining a ratio of alcohol in the engine; determining a fuel injection mode and an injection ratio based on the operating conditions and the alcohol ratio; controlling the engine operation based on the fuel injection mode and the injection ratio; Wherein, the operating conditions at least include the load, temperature and start / stop state of the engine, the alcohol ratio is defined as the ratio of the content of flexible alcohol to the content of fuel, the injection mode includes a direct injection mode, an intake port injection mode and a dual injection mode, and the injection ratio is defined as the ratio of the fuel injection amount in the direct injection mode to the fuel injection amount in the intake port injection mode; The step of determining the fuel injection mode and the injection ratio based on the operating conditions and the alcohol ratio includes: When the load is less than a predetermined load value, the temperature is less than a preset temperature value, or the start-stop state is start, determining that the injection mode is the in-cylinder direct injection mode; When the load is greater than the predetermined load value and the alcohol ratio is close to a maximum value, determining the injection mode to be the dual injection mode and determining the injection ratio to be a first injection ratio, wherein the first injection ratio is defined as a ratio when the fuel injection amount in the direct injection mode is less than the fuel injection amount in the port injection mode; When the load is greater than the predetermined load value and the alcohol ratio is close to a minimum value, determining the injection mode to be the dual injection mode and determining the injection ratio to be a second injection ratio, wherein the second injection ratio is defined as a ratio when the fuel injection amount in the direct injection mode is greater than the fuel injection amount in the port injection mode; When the load is greater than the predetermined load value and the alcohol ratio is between the minimum value and the maximum value, the injection mode is determined to be the dual injection mode, and the injection ratio is determined to be a third injection ratio, wherein the third injection ratio is between the first injection ratio and the second injection ratio.

2. The engine control method according to claim 1, characterized in that: The operating conditions also include the speed of the engine; The step of determining the fuel injection mode and the injection ratio based on the operating conditions and the alcohol ratio includes: When the load is greater than the predetermined load value, the alcohol ratio is close to the minimum value, and the speed is less than a predetermined speed, determining the injection mode to be the dual injection mode, and determining the injection ratio to be the second injection ratio; When the load is greater than the predetermined load value, the alcohol ratio is close to the minimum value, and the speed is greater than the predetermined speed, determining the injection mode to be the dual injection mode, and determining the injection ratio to be a fourth injection ratio; The fourth injection ratio is between the second injection ratio and the third injection ratio.

3. The engine control method according to claim 1, characterized in that: Determining the injection ratio includes: If the alcohol ratio is close to a minimum value, using 1:0 as an initial injection ratio and increasing the fuel injection amount in the port injection mode by a first preset increment to obtain a plurality of injection ratios; If the alcohol ratio is close to a maximum value, using 0:1 as an initial injection ratio and increasing the fuel injection amount in the direct injection mode by a second preset increment to obtain a plurality of injection ratios; The operating condition and the plurality of injection ratios are calibrated, wherein the calibration is related to a rotation speed, a fuel injection time, and an allowable rail pressure of the engine.

4. The engine control method according to claim 3, characterized in that: Determining the injection ratio also includes: Calculating a median value of the alcohol ratio, taking a predicted value of the direct injection ratio under the median value as an initial injection ratio, and increasing or decreasing the fuel injection amount in the direct injection mode by a third preset increment to obtain a plurality of injection ratios, wherein the median value is equal to the sum of the maximum value and the minimum value divided by 2; The operating conditions are calibrated with the plurality of injection ratios.

5. The engine control method according to claim 4, characterized in that: Determining the injection ratio also includes: Obtaining an initial calibration curve based on the maximum value, the median value, and the minimum value; increasing or decreasing the content of the flexible alcohol by a fourth preset increment to obtain a plurality of the alcohol ratios; The multiple alcohol ratios are interpolated and optimized with the initial calibration curve to obtain a final calibration curve.

6. The engine control method according to claim 1, characterized in that: The control method further comprises: Acquiring an oxygen content of the engine, and obtaining an air-fuel ratio of the engine based on the oxygen content; An alcohol ratio in the engine is retrieved based on the air-fuel ratio.

7. The engine control method according to claim 1, characterized in that: The controlling the engine operation based on the fuel injection mode and the injection ratio comprises: At least one of the injection pressure, the injection amount, the injection timing, the intake and exhaust, or the ignition combustion of the engine is controlled based on the fuel injection mode and the injection ratio.

8. The engine control method according to claim 7, characterized in that: The controlling the engine operation based on the fuel injection mode and the injection ratio further includes: Acquire a model output torque and a target output torque of the engine, wherein the model output torque is defined as an actual output torque of the engine based on the fuel injection mode and the injection ratio, and the target output torque is defined as a theoretical output torque of the engine based on the fuel injection mode and the injection ratio; If the model output torque is less than the target output torque, at least one of the injection pressure, injection amount, injection timing, intake and exhaust or ignition combustion of the engine is re-controlled based on the fuel injection mode and the injection ratio.

9. An engine, characterized in that: It comprises a control device, an engine body, an intake system, a fuel supply system and an exhaust after-treatment system; the control device is connected to the engine body, the intake system, the fuel supply system and the exhaust after-treatment system, and is used to execute the control method described in any one of claims 1 to 7 to control the engine; the fuel supply system comprises a first sensor for detecting the alcohol content; the exhaust after-treatment system comprises a second sensor for detecting the oxygen content.

10. An electronic device, characterized in that: The electronic device includes a memory and a processor, the memory stores a computer program, and the processor implements the engine control method according to any one of claims 1 to 7 when executing the computer program.

11. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the engine control method according to any one of claims 1 to 7 is implemented.

12. A vehicle, characterized in that: The vehicle includes an engine, and the engine includes a control device, and the control device is used to execute the engine control method according to any one of claims 1 to 7.

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