Engine low-pressure starting control method under high-pressure oil pump fault mode

Abstract

The invention relates to an engine low-pressure starting control method in a high-pressure oil pump fault mode, which is used for controlling the opening degree of a throttle valve and comprises the following steps of: calculating starting idle speed air quantity according to starting compensation air quantity and cooling machine compensation air quantity; the idle speed demand torque is calculated by multiplying the torque conversion coefficient of the air quantity; calculating an engine starting torque by adding an engine friction torque; calculating an expected throttle flow by multiplying the flow conversion coefficient of the torque; the initial throttle opening degree is obtained; the opening degree of the starting throttle valve is obtained according to the initial throttle valve opening degree and the opening degree of the starting throttle valve in the low-pressure mode; an oil injection mode is controlled, and a primary oil injection pulse represents a number-letter combination code through an index; and normalizing a letter part in the numeric-letter combination code by using binary numbers to generate a binary number code. Compared with the prior art, the engine is started in the fault mode, and limp home is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of engine electronic control systems and relates to an engine low-pressure starting control method in the high-pressure fuel pump failure mode. Background Art

[0002] For an engine, whether the fuel rail pressure is normal directly affects fuel injection and in-cylinder combustion. If the fuel rail fails or there is air in the high-pressure pipeline or other reasons cause the actual fuel rail pressure to not be effectively established, when the engine is in the compression stage, since the piston moves upward causing the in-cylinder pressure to increase, fuel injection in the second half of the compression stroke will cause the fuel to not be effectively injected into the cylinder, resulting in the engine being unable to start. Under low-temperature conditions in winter, due to the low temperature, the atomization effect of the fuel becomes poor, and premature fuel injection causes the fuel to directly remain on the piston or cylinder wall, and the engine cannot be started after multiple attempts, leading to engine oil dilution. Secondly, if the engine intake air volume is still controlled according to the normal starting state, it will result in an excessive intake air volume, an increase in the calculated fuel quantity, and at the same time, during the process of the piston moving upward in the engine, the processes of compression and rising temperature are generated, causing the air flow temperature to further increase. And in the low-pressure mode, the fuel injection volume of the fuel injector is limited, resulting in an overly lean air-fuel mixture in the engine cylinder, causing abnormal combustion and the engine cannot be started.

[0003] The fuel rail pressure failure mode of traditional gasoline engines is single, and independent fuel injection and intake control design cannot be carried out based on the failure mode, which may cause the engine to be unable to start and cannot meet the vehicle safety requirements.

[0004] Patent CN117365774A discloses a direct injection engine fuel injection control method, device, and storage medium. The method includes: fuel injection mode definition: using three-digit characters to represent the single fuel injection pulse width, where the first character represents the fuel injection pulse width serial number, the second character represents the injection angle calculation reference for the current fuel injection pulse width, and the third character represents the absolute or relative calculation method of the injection angle for the current fuel injection pulse width; determining the fuel injection mode according to the engine demand and calculating the injection angle; after the engine controller calculates the total fuel quantity, setting the fuel injection ratio of each fuel injection pulse width in the fuel injection mode, so as to calculate the fuel injection quantity for the corresponding time. However, this patent does not make specific strategy explanations for fuel injection in the high-pressure fuel pump failure mode, which has certain limitations; and the readability of the fuel injection mode is poor. Summary of the Invention

[0005] The purpose of the present invention is to overcome at least one defect of the above-mentioned existing technologies and provide an engine low-pressure starting control method in the high-pressure fuel pump failure mode. The present invention realizes starting the engine in the failure mode and realizes limp home.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention is to provide a method for controlling low-pressure starting of an engine in a high-pressure oil pump failure mode, wherein the method controls the throttle opening, and the method comprises the following steps:

[0008] S1.1. Divide the starting gas volume into a part of the idle gas volume control, and calculate the starting compensation gas volume m start Plus the cooling machine compensation gas volume m cold Calculate the starting idle gas volume m idle , starting idle gas volume m idle The calculation formula is as follows:

[0009] m idle =m start +m cold ;

[0010] S1.2, according to the starting idle gas volume m idle Multiply the torque conversion coefficient k of the gas volume to calculate the idle speed required torque T idle , idle speed required torque T idle The calculation formula is as follows:

[0011] T idle =m idle *k;

[0012] S1.3, according to the idle speed demand torque T idle Plus the engine friction torque F engine Calculate the engine starting torque T start , engine starting torque T start The calculation formula is as follows:

[0013] T start =T idle +F engine ;

[0014] S1.4, according to the engine starting torque T start Calculate the desired throttle flow by multiplying the flow conversion coefficient δ of the torque;

[0015] S1.5. Obtain the initial throttle opening Φ according to the expected throttle flow raw ;

[0016] S1.6, according to the initial throttle opening Φ raw Starting throttle opening Φ in low pressure mode low Take the smaller value to obtain the starting throttle opening Φ start , starting throttle opening Φ start The calculation formula is as follows:

[0017] Φ start =Min(Φ raw ,Φlow );

[0018] The method also controls the fuel injection mode. A single fuel injection pulse is characterized by an alphanumeric combination code, and the alphanumeric combination codes of several fuel injection pulses form an alphanumeric combination code sequence;

[0019] To save the storage space of the engine's electronic control unit (ECU), binary digits are used to standardize the letter part in the alphanumeric combination code to generate a binary digit code, and the binary digit codes of several fuel injection pulses form a binary digit code sequence.

[0020] As a preferred technical solution, the electronic control unit stores the charts required for calculation.

[0021] Furthermore, in step S1.1, the starting compensation air volume m start and the cold engine compensation air volume m cold both adopt the readings of the two-dimensional calibratable MAP table of the engine coolant temperature, and the starting compensation air volume m start and the cold engine compensation air volume m cold in subsequent speed cycles both decrease with time. After each speed cycle, the starting compensation air volume m start and the cold engine compensation air volume m cold are both multiplied by a decreasing coefficient until it reaches 0. The decreasing coefficient adopts the readings of the two-dimensional calibratable MAP table of time, and the setting range of the decreasing coefficient is (0, 1) (>0 and <1);

[0022] In step S1.5, according to the desired throttle flow rate, the transposed inverse MAP table of the throttle opening MAP table is queried to obtain the initial throttle opening Φ raw ;

[0023] In step S1.6, the starting throttle opening Φ low in the low-pressure mode adopts the readings of the two-dimensional calibratable MAP table of the engine coolant temperature.

[0024] Furthermore, in step S1.2, the setting range of the torque conversion coefficient k is 1.1 to 1.8, which can be set according to experience.

[0025] Furthermore, in step S1.3, the engine friction torque F hot is calculated by adding the hot engine friction torque F offset plus the cold engine friction torque compensation F engine , F hot adopts the readings of the three-dimensional calibratable MAP table of the engine speed and the engine load, F offset adopts the readings of the three-dimensional calibratable MAP table of the engine speed and the engine coolant temperature. The calculation formula of the engine friction torque F engine is as follows:

[0026] F engine = F hot + F offset 。

[0027] Further, in step S1.4, the flow conversion coefficient δ needs to consider the engine ignition efficiency and the engine thermal efficiency. The calculation formula of the flow conversion coefficient δ is as follows:

[0028] δ = π * AFR start / η sa / η thermo / H heat ,

[0029] where, π is the pi, AFR start is the target air-fuel ratio for engine starting, η sa is the engine ignition efficiency, which is the reading of a three-dimensional calibratable MAP table using the engine speed and the difference delta between the current ignition angle and the optimal torque ignition angle. η thermo is the engine thermal efficiency, which is the reading of a three-dimensional calibratable MAP table using the engine speed and the engine load. H heat is the calorific value of gasoline.

[0030] Further, a primary fuel injection pulse is characterized by a digital-letter combination code through five indicators. The digital-letter combination codes of several fuel injection pulses form a digital-letter combination code sequence. The fuel injection mode includes the following indicators:

[0031] The first indicator is represented by a positive integer to indicate the fuel injection order;

[0032] The second indicator is represented by the letter A or R to indicate the reference for calculating the fuel injection angle. A means absolute, as an absolute value, representing that the fuel injection angle of this injection is calculated with reference to the absolute calculation reference of the fuel injection angle at the top dead center of compression or the ignition advance angle. R means relative, as a relative value, representing that the fuel injection angle of this injection is calculated with reference to the relative calculation reference of the fuel injection angle at the end position of the previous fuel injection angle;

[0033] The third indicator is represented by the letter S or E to indicate the calculation method of the fuel injection angle. S means SOI (start of injection), as the start angle of fuel injection, representing that the fuel injection angle of this injection is calculated by the crankshaft phase distance from the fuel injection angle calculation reference to the start position of this fuel injection angle. E means EOI (end of injection), as the end angle of fuel injection, representing that the fuel injection angle of this injection is calculated by the crankshaft phase distance from the fuel injection angle calculation reference to the end position of this fuel injection angle;

[0034] The fourth indicator uses the letter D or P to represent the fuel injection method. D is GDI (gasoline direct injection), which is in-cylinder direct injection, representing that this fuel injection pulse uses in-cylinder direct injection as the fuel injection method. P is PFI (port fuel injection), which is port fuel injection, representing that this fuel injection pulse uses port fuel injection as the fuel injection method;

[0035] The fifth indicator uses the letter T or K to represent the absolute calculation reference for the fuel injection angle. T is TDC (top dead center), which is the top dead center of compression, representing that this fuel injection angle uses the top dead center of compression as the absolute calculation reference. K is spark, which is the ignition advance angle, representing that this fuel injection angle uses the ignition advance angle as the absolute calculation reference.

[0036] As a preferred technical solution, when the engine uses an in-cylinder direct injection engine, only in-cylinder direct injection can be used. When the engine uses a dual-injection system engine with both in-cylinder direct injection and port fuel injection functions, in-cylinder direct injection or port fuel injection can be used according to needs.

[0037] As a preferred technical solution, the digital-letter combination codes of several fuel injection pulses in the digital-letter combination code sequence are distinguished by underscores, which is convenient for personnel to identify.

[0038] Furthermore, since the priority of the last injection is the highest, the binary digital codes of several fuel injection pulses are reversed to form a binary digital code sequence. A is assigned 1, R is assigned 0, S is assigned 1, E is assigned 0, D is assigned 1, P is assigned 0, T is assigned 1, and K is assigned 0.

[0039] Furthermore, when the second indicator uses R, the fifth indicator has no actual meaning. At this time, the fifth indicator is default set to T. To simplify the operation, the third indicator is default set to S at this time.

[0040] When the corresponding third indicator uses E, the fourth indicator uses P, and the fifth indicator uses K, it represents that this fuel injection pulse actually does not occur;

[0041] When the binary digital code uses 0111 or 0101, it represents in-cylinder direct injection or port fuel injection. The specific injection position of this fuel injection angle is defined by the relative angle between the fuel injection start angle and the end position of the previous fuel injection angle.

[0042] When the binary digital code uses 0011 or 0001, it represents in-cylinder direct injection or port fuel injection. The specific injection position of this fuel injection angle is defined by the relative angle between the fuel injection end angle and the end position of the previous fuel injection angle.

[0043] To simplify the operation, only the injection start angle is used as the injection angle calculation method at this time, that is, the binary digital code uses 0111 or 0101 instead of 0011 or 0001.

[0044] When the binary digital code uses 0110, 0100 or 0010, it has no actual meaning.

[0045] When the binary digital code uses 0000, it means that the injection pulse does not actually occur in this time.

[0046] During the setting process of the final injection mode, it is necessary to avoid using the end position of the previous injection angle as the relative calculation reference for the injection angle of the first injection, that is, the second index of the injection mode of the first injection cannot start injection with R and is default set to A.

[0047] As a preferred technical solution, the end position of the fuel injection and discharge of the last injection cannot exceed the injection cut-off angle Ф end , because the engine is in the piston upstroke stage and the fuel rail is in a low oil pressure state. If the injection angle is not clamped, the fuel may not be injected into the cylinder.

[0048] Furthermore, the method also controls the injection ratio. The calculation of the injection quantity for several times includes the following steps:

[0049] S2.1. Since the priority of the last injection is the highest, the injection quantity M of the last injection set first last The proportion relative to the total injection quantity M is R last , R last Uses the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R Last The setting range of is 0 to 1. According to R last Calculate the injection quantity M of the last injection last The calculation formula is as follows:

[0050] M last = M * R last ;

[0051] S2.2. The remaining total injection quantity M - M last Is used for the distribution of the previous several injections. The injection quantity M of the xth injection set x The proportion relative to the remaining total injection quantity M - M last Is R x , R x Uses the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R x The setting range of is 0 to 1, and satisfies ΣR x = 1, where Rlast Not included in the calculation, according to R x Calculate the fuel injection quantity M for the xth time x , and the calculation formula is as follows:

[0052] M x =(M - M last ) * R x .

[0053] As a preferred technical solution, before step S2.1, the electronic control unit calculates the total fuel injection quantity M according to the required torque, actual intake air quantity, and air-fuel ratio parameters.

[0054] Furthermore, the method also controls the rail pressure operation, and the rail pressure operation mode includes the following steps:

[0055] The plunger of the high-pressure oil pump contacts the driving cam. Through the rotary motion of the driving cam, the reciprocating motion of the plunger is realized. When the plunger moves upward, in the fault mode, the electronic control unit of the engine does not control the solenoid valve of the high-pressure oil pump, and the solenoid valve is in the open state. Part of the fuel enters the high-pressure pipeline through the one-way valve, and part of the fuel is directly returned to the low-pressure pipeline through the extrusion of the upward movement of the plunger and through the solenoid valve. In this way, in the fault mode, the fuel pressure in the high-pressure pipeline operates in the low-pressure state, and the fuel pressure in the high-pressure pipeline ≤ the fuel pressure in the low-pressure pipeline.

[0056] As a preferred technical solution, the plunger includes a plunger base, a driving return spring, and a plunger push rod. The outside of the plunger base contacts the driving cam, and the inside is connected to the plunger push rod and the driving return spring. The driving return spring is sleeved outside the plunger push rod. The driving cam pushes the plunger base, presses the plunger push rod, and moves the plunger upward. The driving return spring pushes the plunger base, presses out the plunger push rod, and moves the plunger downward.

[0057] As a preferred technical solution, the solenoid valve includes a solenoid push rod, a solenoid coil, and a solenoid return spring. The solenoid coil is sleeved outside the solenoid push rod, and the outer end of the solenoid push rod is connected to the solenoid return spring. When the solenoid coil is powered off, the solenoid return spring pushes the solenoid push rod into the high-pressure oil pump to open the solenoid valve. When the solenoid coil is powered on, the solenoid coil attracts the solenoid push rod to press out of the high-pressure oil pump to close the solenoid valve. The solenoid valve controls the switch of the low-pressure pipeline.

[0058] As a preferred technical solution, the one-way valve controls the switch of the high-pressure pipeline.

[0059] One of the technical solutions of the present invention is to provide an engine low-pressure starting control device in the fault mode of the high-pressure oil pump, including a memory, a processor, and a computer program stored on the memory. The processor executes the computer program to implement the steps of the method.

[0060] One of the technical solutions of the present invention is to provide a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the described method are implemented.

[0061] One of the technical solutions of the present invention is to provide a computer program product, including a computer program, and when the computer program is executed by a processor, the steps of the described method are implemented.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] (1) Based on the engine fuel rail pressure fault mode, the present invention designs the rail pressure operation mode, injection strategy, and throttle opening limit strategy in this mode. Even in the fault mode, the engine can be started, realizing the customer's limp home function requirement. In an emergency, the customer can drive the vehicle to the repair station to meet the vehicle safety needs.

[0064] (2) In the present invention, the rail pressure operation mode and injection strategy allow the injection angle to be adjusted in the low-pressure mode, and fuel injection is carried out within a reasonable range, realizing better atomization of fuel in the cylinder at the starting moment, which is beneficial to more efficient ignition of the engine. Combining the throttle opening limit strategy to reduce the throttle opening, restrict the intake air flow, and suppress the excessive temperature of the air flow, realizing good mixing of fuel and air, improving the atomization effect, and increasing the probability of successful engine start. The present invention can ensure the engine start at different temperatures (engine coolant temperature). Even in extremely cold regions and high-pressure fault modes, the engine can be normally started and can be extended to the development of engine products.

[0065] (3) The present invention uses a more intuitive computer binary method to encode the injection mode, with good readability. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 It is a schematic diagram of the high-pressure oil pump working in the rail pressure control mode of the engine low-pressure start control method in the high-pressure oil pump fault mode in the embodiment of the present invention;

[0067] Figure 2 It is a schematic diagram of the injection angle of the injection strategy in the engine low-pressure start control method in the high-pressure oil pump fault mode in the embodiment of the present invention;

[0068] Figure 3 It is a schematic diagram of the throttle opening limit strategy in the engine low-pressure start control method in the high-pressure oil pump fault mode in the embodiment of the present invention.

[0069] Explanation of the marks in the figure:

[0070] 1 - Driving cam, 2 - Driving return spring, 3 - Plunger, 4 - High-pressure pipeline, 5 - Check valve, 6 - Actuating valve, 7 - Low-pressure pipeline. Specific embodiments

[0071] The present invention will be described in detail below in conjunction with specific embodiments. These embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0072] Embodiment:

[0073] An engine low-pressure starting control method in the high-pressure fuel pump failure mode, including the rail pressure operation mode, injection strategy, and throttle opening limit strategy in the high-pressure fuel pump failure mode, can realize low-pressure starting of the engine in the high-pressure fuel pump failure mode and achieve the limp home function.

[0074] Control the rail pressure operation in the high-pressure fuel pump failure mode, as Figure 1 shown, the specific steps of the rail pressure operation mode are as follows:

[0075] The plunger 3 of the high-pressure fuel pump contacts the driving cam 1. Through the rotary motion of the driving cam 1, the reciprocating motion of the plunger 3 is realized. When the plunger 3 moves upward, in the failure mode, the engine's electronic control unit (ECU) does not control the actuating valve 6 of the high-pressure fuel pump, and the actuating valve 6 is in the open state. Part of the fuel enters the high-pressure pipeline 4 through the check valve 5, and part of the fuel is squeezed by the upward movement of the plunger 3 and directly returns to the low-pressure pipeline 7 through the actuating valve 6. In this way, in the failure mode, the fuel pressure in the high-pressure pipeline 4 operates at a low pressure, and the fuel pressure in the high-pressure pipeline 4 ≤ the fuel pressure in the low-pressure pipeline 7;

[0076] The plunger 3 includes a plunger base, a driving return spring 2, and a plunger push rod. The outside of the plunger base contacts the driving cam 1, and the inside is connected to the plunger push rod and the driving return spring 2. The driving return spring 2 is sleeved outside the plunger push rod. The driving cam 1 pushes the plunger base, presses the plunger push rod, and moves the plunger 3 upward. The driving return spring 2 pushes the plunger base, presses out the plunger push rod, and moves the plunger 3 downward;

[0077] The actuating valve includes an actuating push rod, an actuating coil, and an actuating return spring. The actuating coil is sleeved outside the actuating push rod, and the outer end of the actuating push rod is connected to the actuating return spring. When the actuating coil is powered off, the actuating return spring pushes the actuating push rod into the high-pressure fuel pump to open the actuating valve. When the actuating coil is powered on, the actuating coil attracts the actuating push rod to press out of the high-pressure fuel pump to close the actuating valve. The actuating valve controls the opening and closing of the low-pressure pipeline 7;

[0078] The check valve 5 controls the opening and closing of the high-pressure pipeline 4.

[0079] Under the fault mode of the high-pressure oil pump, the injection mode is controlled. A single injection pulse is characterized by a digital-letter combination code through five indicators. The digital-letter combination codes of several injection pulses form a digital-letter combination code sequence. The specific indicators of the injection mode are as follows:

[0080] The first indicator represents the injection order with a positive integer. For example, 1, 2, 3, and 4 represent the 1st, 2nd, 3rd, and 4th injections respectively;

[0081] The second indicator represents the reference for calculating the injection angle with the letter A or R. A means absolute, representing that the injection angle of this injection is calculated with the absolute calculation reference of the injection angle at the compression top dead center or the ignition advance angle. R means relative, representing that the injection angle of this injection is calculated with the relative calculation reference of the injection angle at the end position of the previous injection angle;

[0082] The third indicator represents the calculation method of the injection angle with the letter S or E. S means SOI (start of injection), representing that the injection angle of this injection is calculated by the crankshaft phase distance from the injection angle calculation reference to the start position of this injection angle. E means EOI (end of injection), representing that the injection angle of this injection is calculated by the crankshaft phase distance from the injection angle calculation reference to the end position of this injection angle;

[0083] The fourth indicator represents the injection method with the letter D or P. D means GDI (gasoline direct injection), representing that this injection pulse is in the form of gasoline direct injection. P means PFI (port fuel injection), representing that this injection pulse is in the form of port fuel injection;

[0084] When the engine selects a gasoline direct injection engine, only GDI can be selected. When the engine selects a dual injection system engine with both gasoline direct injection and port fuel injection functions, GDI or PFI can be selected according to needs;

[0085] The fifth indicator represents the absolute calculation reference of the injection angle with the letter T or K. T means TDC (top dead center), representing that the injection angle of this injection is calculated with the compression top dead center as the absolute calculation reference. K means spark, representing that the injection angle of this injection is calculated with the ignition advance angle as the absolute calculation reference;

[0086] When the second indicator selects R, the fifth indicator has no actual meaning. At this time, the fifth indicator is default set to T. For the sake of simplifying the operation, the third indicator is default set to S at this time,

[0087] When the corresponding third index selects E, the fourth index selects P, and the fifth index selects K, it means that the fuel injection pulse did not actually occur during this time.

[0088] The digital-letter combination codes of several fuel injection pulses in the digital-letter combination code sequence are distinguished by underscores, which is convenient for personnel to identify.

[0089] The following lists the letter combination codes of some fuel injection pulses in the high-pressure fuel pump failure mode. The specific codes are as follows:

[0090] The letter combination code ASDT. For this fuel injection pulse, gasoline direct injection GDI (D) in the cylinder is selected, and the specific injection position of this fuel injection angle is defined by the absolute angle (A) between the start of injection angle SOI (S) and the top dead center of compression TDC (T).

[0091] The letter combination code AEDT. For this fuel injection pulse, gasoline direct injection GDI (D) in the cylinder is selected, and the specific injection position of this fuel injection angle is defined by the absolute angle (A) between the end of injection angle EOI (E) and the top dead center of compression TDC (T).

[0092] The letter combination code AEDK. For this fuel injection pulse, gasoline direct injection GDI (D) in the cylinder is selected, and the specific injection position of this fuel injection angle is defined by the absolute angle (A) between the end of injection angle EOI (E) and the ignition advance angle (K).

[0093] The letter combination code RSDT. For this fuel injection pulse, gasoline direct injection GDI (D) in the cylinder is selected, and the specific injection position of this fuel injection angle is defined by the relative angle (R) between the start of injection angle SOI (S) and the end position of the previous fuel injection angle.

[0094] In order to save the storage space of the engine's electronic control unit, binary numbers are used to standardize the letter part in the digital-letter combination code to generate binary digital codes. Since the priority of the last injection is the highest, the binary digital codes of several fuel injection pulses are arranged in reverse order to form a binary digital code sequence. The corresponding relationship between the digital-letter combination code sequence and the binary digital code sequence is shown in Table 1. Among them, A is assigned 1, R is assigned 0, S is assigned 1, E is assigned 0, D is assigned 1, P is assigned 0, T is assigned 1, and K is assigned 0.

[0095] When the binary digital code selects 0111 or 0101, it represents gasoline direct injection GDI or port fuel injection PFI in the cylinder, and the specific injection position of this fuel injection angle is defined by the relative angle between the start of injection angle SOI and the end position of the previous fuel injection angle.

[0096] When the binary digital code selects 0011 or 0001, it represents gasoline direct injection (GDI) in the cylinder or port fuel injection (PFI). The specific injection position of this injection angle is defined by the relative angle between the end of injection angle (EOI) and the end position of the previous injection angle.

[0097] To simplify the operation, only the start of injection angle (SOI) is used as the injection angle calculation method at this time, that is, the binary digital code uses 0111 or 0101 instead of 0011 or 0001.

[0098] When the binary digital code selects 0110, 0100 or 0010, it has no actual meaning.

[0099] When the binary digital code selects 0000, it means that this injection pulse does not actually occur.

[0100] Table 1 Correspondence between the digital-letter combination code sequence and the binary digital code sequence of the injection mode in the injection strategy of the engine low-pressure start control method in the high-pressure fuel pump failure mode

[0101]

[0102] The following lists the digital-letter combination code sequences and binary digital code sequences of some injection pulses in the high-pressure fuel pump failure mode when the upper limit is 4 injections. The specific sequences are as follows:

[0103] The digital-letter combination code sequence 1ASDT only selects the first injection, gasoline direct injection (GDI) in the cylinder (D). The specific injection position of this injection angle is defined by the absolute angle (A) between the start of injection angle (SOI) (S) and top dead center (TDC) (T). The binary digital code sequence is 0000 0000 0000 1111;

[0104] The digital-letter combination code sequence 1ASDT_2AEDT selects a total of 2 injections. For the first injection, gasoline direct injection (GDI) in the cylinder (D), the specific injection position of this injection angle is defined by the absolute angle (A) between the start of injection angle (SOI) (S) and top dead center (TDC) (T). For the second injection, gasoline direct injection (GDI) in the cylinder (D), the specific injection position of this injection angle is defined by the absolute angle (A) between the end of injection angle (EOI) (E) and top dead center (TDC) (T). The binary digital code sequence is 0000 0000 10111111;

[0105] The alphanumeric code sequence is 1ASDT_2ASDT_4AEDK. A total of 3 injections are selected. For the 1st and 2nd injections, gasoline direct injection GDI (D) is used. The specific injection position of this injection angle is defined by the absolute angle (A) between the start of injection (SOI) (S) and top dead center (TDC) (T) of compression. For the 4th injection, gasoline direct injection GDI (D) is used. The specific injection position of this injection angle is defined by the absolute angle (A) between the end of injection (EOI) (E) and the ignition advance angle (K). The binary digital code sequence is 1010 0000 1111 1111.

[0106] The following lists the injection angles in the high-pressure fuel pump fault mode during 4 injections, as Figure 2 shown. The specific angles are as follows:

[0107] The injection angle Ф1 of the 1st injection is in the form of the start of injection (SOI), with top dead center (TDC) of compression as the absolute calculation reference;

[0108] During the setting process of the final injection mode, it is necessary to avoid using the end position of the previous injection angle as the relative calculation reference for the injection angle Ф1 of the 1st injection. That is, the second index of the injection mode of the 1st injection cannot start injection with R, and the default setting is A;

[0109] The injection angle Ф x of the xth injection can be in the form of the start of injection (SOI) or the end of injection (EOI), with top dead center (TDC) of compression as the absolute calculation reference, or in the form of the start of injection (SOI), with the end position of the previous injection angle as the relative calculation reference, where x is a positive integer from 2 to 4;

[0110] The end position of the injection angle of the last injection cannot exceed the injection cut-off angle Ф end , because the engine is in the piston upward stroke and the fuel rail is in a low oil pressure state. If the injection angle is not clamped, the fuel may not be injected into the cylinder.

[0111] The electronic control unit stores the charts required for calculation.

[0112] The injection ratio is controlled in the high-pressure fuel pump fault mode. The specific steps for calculating the injection quantity several times are as follows:

[0113] S1.1. The electronic control unit calculates the total injection quantity M according to the required torque, actual intake air quantity, and air-fuel ratio parameters;

[0114] S1.2. Since the priority of the last injection is the highest, the injection quantity M last set first for the last injection accounts for a ratio R last of the total injection quantity M, and R lastSelect the three-dimensional calibratable MAP table reading. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R Last is set in the range of 0 to 1. According to R last calculate the last injection quantity M last , and the calculation formula is as follows:

[0115] M last = M * R last ;

[0116] S1.3. The remaining total injection quantity M - M last is used for the distribution of the previous several injections. The set injection quantity M x of the x-th injection relative to the remaining total injection quantity M - M last is R x , and R x selects the three-dimensional calibratable MAP table reading. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R x is set in the range of 0 to 1, and satisfies ΣR x = 1, where R last is not included in the calculation. According to R x calculate the injection quantity M x of the x-th injection, and the calculation formula is as follows:

[0117] M x = (M - M last ) * R x .

[0118] The following lists a calculation method for the injection ratio during 4 injections. The specific steps are as follows:

[0119] S1.1. The electronic control unit calculates the total injection quantity M according to the required torque, actual intake air quantity, and air-fuel ratio parameters;

[0120] S1.2. Since the priority of the 4th injection is the highest, the set injection quantity M4 of the 4th injection relative to the total injection quantity M is R4. R4 selects the three-dimensional calibratable MAP table reading. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R4 is set in the range of 0 to 1. According to R4, calculate the injection quantity M4 of the 4th injection. The calculation formula is as follows:

[0121] M4 = M * R4;

[0122] S1.3. The remaining total fuel injection amount M - M4 is used for the distribution of the previous 3 injections. The proportion of the set first fuel injection amount M1 relative to the remaining total fuel injection amount M - M4 is R1. R1 selects the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the setting range of the vertical coordinate R1 is 0 to 1. Calculate the first fuel injection amount M1 according to R1, and the calculation formula is as follows:

[0123] M1 = (M - M4) * R1;

[0124] The proportion of the set second fuel injection amount M2 relative to the remaining total fuel injection amount M - M4 is R2. R2 selects the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the setting range of the vertical coordinate R2 is 0 to 1. Calculate the second fuel injection amount M2 according to R2, and the calculation formula is as follows:

[0125] M2 = (M - M4) * R2;

[0126] The proportion of the set third fuel injection amount M3 relative to the remaining total fuel injection amount M - M4 is R3. R3 selects the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate R3 satisfies R3 = 1 - R1 - R2. Calculate the third fuel injection amount M3 according to R3, and the calculation formula is as follows:

[0127] M3 = (M - M4) * R3.

[0128] Control the throttle opening in the high-pressure fuel pump fault mode, as Figure 3 shown. The specific steps for restricting the throttle opening are as follows:

[0129] S2.1. Divide the starting air volume into a part of the idle air volume control. Calculate the starting idle air volume m start by adding the starting compensation air volume m cold and the cold engine compensation air volume m idle . Among them, the starting compensation air volume m start and the cold engine compensation air volume m cold in the initial speed cycle both select the readings of a two-dimensional calibratable MAP table of the engine coolant temperature, and the starting compensation air volume m start and the cold engine compensation air volume m cold in the subsequent speed cycles both decrease with time. After each speed cycle, the starting compensation air volume m start and the cold engine compensation air volume m cold are both multiplied by the decreasing coefficient until it reaches 0. The decreasing coefficient selects the readings of a two-dimensional calibratable MAP table of time, and the setting range of the decreasing coefficient is (0, 1) (>0 and <1). The starting idle air volume m idleThe calculation formula is as follows:

[0130] m idle = m start + m cold ;

[0131] S2.2. Calculate the idle demand torque T according to the starting idle air volume m idle multiplied by the torque conversion coefficient k of the air volume. The setting range of the torque conversion coefficient k is 1.1 - 1.8, which can be set according to experience. The calculation formula of the idle demand torque T idle is as follows: idle The calculation formula is as follows:

[0132] T idle = m idle * k;

[0133] S2.3. Calculate the engine starting torque T idle by adding the engine friction torque F engine . Among them, calculate the engine friction torque F start according to the warm engine friction torque F hot plus the cold engine friction torque compensation F offset . Select the three-dimensional calibratable MAP table readings of the engine speed and the engine load for F engine , select the three-dimensional calibratable MAP table readings of the engine speed and the engine coolant temperature for F hot . The calculation formulas of the engine starting torque T offset and the engine friction torque F start are as follows: engine The calculation formula is as follows:

[0134] T start = T idle + F engine ,

[0135] F engine = F hot + F offset ;

[0136] S2.4. Calculate the desired throttle flow according to the engine starting torque T start multiplied by the flow conversion coefficient δ of the torque. Among them, the flow conversion coefficient δ needs to consider the engine ignition efficiency and the engine thermal efficiency. The calculation formula of the flow conversion coefficient δ is as follows:

[0137] δ = π * AFR start / η sa / η thermo / H heat ,

[0138] Among them, π is the pi, AFR startis the target air-fuel ratio for engine starting, η sa is the engine ignition efficiency. The three-dimensional calibratable MAP table readings of the engine speed and the difference delta between the current ignition angle and the optimal torque ignition angle are selected, η thermo is the engine thermal efficiency. The three-dimensional calibratable MAP table readings of the engine speed and the engine load are selected, H heat is the calorific value of gasoline. For example, the calorific value of common 92# gasoline is generally 43 J / mg;

[0139] S2.5. According to the desired throttle flow rate, query the transposed inverse MAP table of the throttle opening MAP table to obtain the initial throttle opening Φ raw ;

[0140] S2.6. According to the initial throttle opening Φ raw and the starting throttle opening Φ low in the low-pressure mode, take the smaller value to obtain the starting throttle opening Φ start , where the starting throttle opening Φ low in the low-pressure mode selects the two-dimensional calibratable MAP table readings of the engine coolant temperature. The calculation formula for the starting throttle opening Φ start is as follows:

[0141] Φ start = Min(Φ raw , Φ low ).

[0142] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. An engine low-pressure starting control method in the failure mode of a high-pressure oil pump, characterized in that, This method controls the throttle opening, and the method includes the following steps: S1.

1. Calculate the starting idle gas volume m start by adding the starting compensation gas volume m cold and the cold engine compensation gas volume m idle ; S1.

2. Calculate the idle demand torque T according to the starting idle air volume m idle multiplied by the torque conversion coefficient k of the air volume idle ; S1.

3. Calculate the engine starting torque T idle by adding the engine friction torque F engine to the idle demand torque T start ; S1.

4. Calculate the expected throttle flow rate according to the engine starting torque T start by multiplying it with the flow conversion coefficient δ of the torque S1.

5. Obtain the initial throttle opening Φ according to the desired throttle flow rate raw ; S1.

6. Obtain the starting throttle opening Φ according to the smaller value between the initial throttle opening Φ raw and the starting throttle opening Φ in the low-pressure mode low ; start ; This method also controls the fuel injection mode. A single fuel injection pulse is characterized by an alphanumeric combination code, and the alphanumeric combination codes of several fuel injection pulses form an alphanumeric combination code sequence; Binary digits are used to standardize the letter part in the alphanumeric combination code to generate a binary digit code, and the binary digit codes of several fuel injection pulses form a binary digit code sequence.

2. The engine low-pressure starting control method in the high-pressure oil pump failure mode according to claim 1, wherein, The starting compensation air volume m for the initial speed cycle in step S1.1 start and the cold engine compensation air volume m cold both adopt the readings of the two-dimensional calibratable MAP table of the engine coolant temperature, and the starting compensation air volume m for subsequent speed cycles start and the cold engine compensation air volume m cold both decrease with time. After each speed cycle, the starting compensation air volume m start and the cold engine compensation air volume m cold are both multiplied by a decreasing coefficient until it reaches 0. The decreasing coefficient adopts the readings of the two-dimensional calibratable MAP table of time, and the setting range of the decreasing coefficient is (0, 1); In step S1.5, according to the expected throttle flow rate, query the transposed inverse MAP table of the throttle opening MAP table to obtain the initial throttle opening Φ raw ; Throttle opening Φ at startup in the low-pressure mode in step S1.6 low Use the two-dimensional calibratable MAP table reading of the engine coolant temperature.

3. A method for controlling the low-pressure starting of an engine in the failure mode of a high-pressure oil pump, characterized in that In step S1.2, the setting range of the torque conversion coefficient k is 1.1 - 1.

8.

4. A method for controlling the low-pressure starting of an engine in the failure mode of a high-pressure oil pump, characterized in that, In step S1.3, according to the friction torque F of the heat engine hot plus the cold engine friction torque compensation F offset calculate the engine friction torque F engine , F hot Adopt the three-dimensional calibratable MAP table readings of the engine speed and engine load, F offset Adopt the three-dimensional calibratable MAP table readings of the engine speed and engine coolant temperature.

5. A method for controlling the low-pressure starting of an engine in the failure mode of a high-pressure oil pump, characterized in that, In step S1.4, the calculation formula of the flow conversion coefficient δ is as follows: δ = π * AFR start / η sa / η thermo / H heat , where, π is the pi, AFR start is the target air-fuel ratio for engine starting, η sa is the engine ignition efficiency, which adopts the three-dimensional calibratable MAP table readings of the engine speed and the difference delta between the current ignition angle and the optimal torque ignition angle, η thermo is the engine thermal efficiency, which adopts the three-dimensional calibratable MAP table readings of the engine speed and the engine load, H heat is the calorific value of gasoline.

6. The engine low-pressure starting control method in the high-pressure oil pump failure mode according to claim 1, wherein, A single fuel injection pulse is characterized by an alphanumeric combination code through five indicators, and the alphanumeric combination codes of several fuel injection pulses are sequentially arranged to form an alphanumeric combination code sequence. The fuel injection mode includes the following indicators: The first indicator represents the fuel injection order with a positive integer; The second indicator represents the fuel injection angle calculation reference with the letter A or R. A is used as an absolute value, representing that the fuel injection angle of this time is calculated with the absolute calculation reference of the fuel injection angle at the compression top dead center or the ignition advance angle. R is used as a relative value, representing that the fuel injection angle of this time is calculated with the relative calculation reference of the fuel injection angle at the end position of the previous fuel injection angle; The third indicator represents the fuel injection angle calculation method with the letter S or E. S is used as the fuel injection start angle, representing that the fuel injection angle of this time is calculated by the crankshaft phase distance from the fuel injection angle calculation reference to the start position of this fuel injection angle. E is used as the fuel injection end angle, representing that the fuel injection angle of this time is calculated by the crankshaft phase distance from the fuel injection angle calculation reference to the end position of this fuel injection angle; The fourth indicator represents the fuel injection method with the letter D or P. D is used for direct injection in the cylinder, representing that this fuel injection pulse uses direct injection in the cylinder as the fuel injection method. P is used for port injection, representing that this fuel injection pulse uses port injection as the fuel injection method; The fifth indicator represents the absolute calculation reference of the fuel injection angle with the letter T or K. T is used as the compression top dead center, representing that the fuel injection angle of this time is calculated with the compression top dead center as the absolute calculation reference. K is used as the ignition advance angle, representing that the fuel injection angle of this time is calculated with the ignition advance angle as the absolute calculation reference.

7. The engine low-pressure starting control method in the high-pressure oil pump failure mode according to claim 6, characterized in that, The binary digit codes of several fuel injection pulses are arranged in reverse order to form a binary digit code sequence. A is assigned 1, R is assigned 0, S is assigned 1, E is assigned 0, D is assigned 1, P is assigned 0, T is assigned 1, and K is assigned 0.

8. A method for controlling the low-pressure starting of an engine in the failure mode of a high-pressure oil pump, characterized in that, When the second indicator uses R, the fifth indicator has no actual meaning, and at this time, the fifth indicator is default set to T. When the corresponding third indicator uses E, the fourth indicator uses P, and the fifth indicator uses K, it means that this fuel injection pulse actually does not occur; When the binary digit code uses 0111 or 0101, it represents direct injection in the cylinder or port injection, and the specific injection position of this fuel injection angle is defined by the relative angle between the fuel injection start angle and the end position of the previous fuel injection angle. When the binary digit code uses 0011 or 0001, it represents direct injection in the cylinder or port injection, and the specific injection position of this fuel injection angle is defined by the relative angle between the fuel injection end angle and the end position of the previous fuel injection angle. When the binary digital code is 0110, 0100 or 0010, it has no actual meaning. When the binary digital code is 0000, it means that the fuel injection pulse does not actually occur this time. The second index of the fuel injection mode for the first injection is default set to A.

9. The engine low-pressure starting control method in the high-pressure oil pump failure mode according to claim 1, wherein The method also controls the fuel injection ratio, and the calculation of the fuel injection amount for several times includes the following steps: S2.

1. The last fuel injection quantity M set preferentially last The proportion relative to the total fuel injection quantity M is R last , R last Adopt the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate is R Last The setting range of is 0 to 1. According to R last Calculate the last fuel injection quantity M last ; S2.

2. Set the fuel injection quantity M for the x-th time x The relative remaining total fuel injection quantity M - M last has a proportion of R x , R x Adopt the readings of a three-dimensional calibratable MAP table. The horizontal and vertical coordinates of the three-dimensional calibratable MAP table are the engine speed and the engine load respectively, and the vertical coordinate is R x The setting range of is 0 to 1, and satisfies ΣR x = 1, where R last is not included in the calculation. Calculate the fuel injection quantity M for the x-th time according to R x . x .

10. A method for controlling the low-pressure starting of an engine in the failure mode of a high-pressure oil pump, characterized in that, The method also controls the rail pressure operation, and the rail pressure operation mode includes the following steps: The plunger (3) of the high-pressure fuel pump contacts the driving cam (1). Through the rotary motion of the driving cam (1), the reciprocating motion of the plunger (3) is realized. When the plunger (3) moves upward, in the fault mode, the electronic control unit of the engine does not control the actuator valve (6) of the high-pressure fuel pump, and the actuator valve (6) is in the open state. A part of the fuel enters the high-pressure pipeline (4) through the check valve (5), and a part of the fuel is squeezed by the upward movement of the plunger (3) and directly returns to the low-pressure pipeline (7) through the actuator valve (6). In this way, in the fault mode, the fuel pressure in the high-pressure pipeline (4) operates in the low-pressure state, and the fuel pressure in the high-pressure pipeline (4) ≤ the fuel pressure in the low-pressure pipeline (7).

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