A vehicle low temperature starting method based on electric energy distribution

Abstract

The application discloses a kind of vehicle low temperature starting method based on electric energy distribution, vehicle determines current real-time battery power percentage when starting gear and judges starting temperature, if starting temperature is lower than temperature threshold, whether starting vehicle is determined according to real-time battery power percentage;If it is determined to start the vehicle, the first preheating time of preheating grid before engine starting is determined, or the second preheating time of preheating grid before engine starting and the third preheating time of boiler are determined;Control preheating grid intake preheating first preheating time, or control preheating grid intake preheating second preheating time and boiler preheating third preheating time;After preheating time reaches, starting motor relay is closed to start dragging engine, and after engine speed reaches idle speed, vehicle low temperature starting is successful.The application significantly improves the reliability of vehicle starting in low temperature environment, reduces the starting difficulty problem caused by low temperature, improves user experience, and ensures normal use of vehicle.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of automobile control, and particularly relates to a vehicle low-temperature starting method based on electric energy distribution. BACKGROUND

[0002] Currently, automatic transmissions are increasingly used, and it is more difficult to start a vehicle with an automatic transmission at low temperature because the engine cannot be completely disconnected from the transmission through a clutch. Auxiliary technical means such as intake preheating and boiler heating are needed, and the starting time is long and the operation is complex.

[0003] Currently, the engine is started at low temperature by heating the engine coolant and the intake air, which can realize the circulation heating of the engine coolant and the intake air of multiple cylinders of the engine at the same time, and can complete the rapid starting of the engine in an extremely cold environment in a short time. The starting condition of this method does not consider the battery power factor, which may cause starting failure due to low power. In addition, it does not judge the starting resistance at different temperatures, which may increase the risk of starting failure. SUMMARY

[0004] The purpose of the present application is to solve the problems in the background art and provide a vehicle low-temperature starting method based on electric energy distribution.

[0005] The technical scheme adopted by the present application is as follows: a vehicle low-temperature starting method based on electric energy distribution, determining the current real-time battery power percentage and the starting temperature when the vehicle is in the starting gear, and determining whether to start the vehicle according to the real-time battery power percentage if the starting temperature is lower than the temperature threshold.

[0006] If it is determined to start the vehicle, the first starting torque without boiler preheating is calculated, the first preheating time of the preheating grid before the engine starts is determined based on the first starting torque, or the second starting torque with boiler preheating is calculated, the second preheating time of the preheating grid and the third preheating time of the boiler before the engine starts are determined based on the second starting torque, or the fourth preheating time of the preheating grid and the fifth preheating time of the boiler before the engine starts are determined based on the second starting torque.

[0007] The preheating grid intake air is preheated for the first preheating time, or the preheating grid intake air is preheated for the second preheating time and the boiler is preheated for the third preheating time, or the preheating grid intake air is preheated for the fourth preheating time and the boiler is preheated for the fifth preheating time.

[0008] After the preheating time is reached, the starting motor relay is closed to start the engine, and when the engine speed reaches the idle speed, the vehicle low-temperature starting is successful.

[0009] Further, the starting temperature is determined by the following formula:

[0010]

[0011] Wherein, T is the starting temperature; T e is the ambient temperature; T w is the initial engine coolant temperature; T o is the initial engine oil temperature; T t is the initial transmission oil temperature; A1, A2, A3, A4 are the weight coefficients of the ambient temperature, the initial engine coolant temperature, the initial engine oil temperature, and the initial transmission oil temperature, respectively, and A1+A2+A3+A4=1.

[0012] Further, the determination process of the real-time battery percentage is as follows:

[0013] When the vehicle is powered on, the instantaneous battery percentage when the vehicle is powered on is determined according to the battery voltage value, the battery aging correction coefficient, and the first correction coefficient;

[0014] The real-time battery percentage is calculated by the formula according to the instantaneous battery percentage,

[0015]

[0016] Wherein, SOC is the real-time battery percentage; SOC' is the instantaneous battery percentage; V is the real-time voltage of the battery; I is the real-time total current of the battery; t is the time period between the time when the vehicle is powered on and the time when the vehicle reaches the starting gear.

[0017] Further, the determination of whether to start the vehicle according to the real-time battery percentage comprises:

[0018] If the real-time battery percentage is less than the first SOC set value, the vehicle is not started;

[0019] If the real-time battery percentage is greater than or equal to the first SOC set value and less than the second SOC set value, an alarm of low battery percentage is issued, and a pop-up window prompts the driver to select whether to start the vehicle;

[0020] If the real-time battery percentage is greater than or equal to the second SOC set value, the vehicle is directly determined to be started.

[0021] Further, the first starting torque or the second starting torque is determined by the following formula:

[0022] M=M s +M e -M fe -M ft

[0023] Wherein, M is the starting torque; M s is the torque provided by the starting motor; M ethe power moment provided for fuel combustion; M fe the resistance moment of the engine; M ft the resistance moment of the gearbox.

[0024] Further, the first preheating time of the preheating grid before the engine starts is determined based on the first starting torque, or the second preheating time of the preheating grid and the third preheating time of the boiler are determined based on the second starting torque, or the fourth preheating time of the preheating grid and the fifth preheating time of the boiler are determined based on the second starting torque, which includes:

[0025] The shortest starting time without preheating the boiler is calculated based on the first formula containing the first starting torque, if there is a positive real solution, the first preheating time of the preheating grid before the engine starts is determined based on the positive real solution; if there is no positive real solution, the shortest starting time with preheating the boiler is calculated based on the second formula containing the second starting torque;

[0026] If there is a positive real solution, the second preheating time of the preheating grid and the third preheating time of the boiler are determined based on the positive real solution; if there is no positive real solution, the fourth preheating time of the preheating grid and the fifth preheating time of the boiler are determined based on the calibration preheating time.

[0027] Further, the first formula is:

[0028]

[0029] 0 < t < 10 a ≤ 10

[0030] 0 ≤ t1 ≤ 45

[0031] f7(t) = t1 + t a

[0032] Wherein, f7(t) is the starting time without preheating the boiler; t1 is the first preheating time; t a is the theoretical drag time of the engine without preheating the boiler; P air is the rated power of the preheating grid; P s ′ is the power of the starting motor when it just starts to drag and the fuel has not been burned yet; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum amount of electricity that can be used for the current vehicle starting prediction; J is the rotational inertia of the engine with the gearbox during the starting stage; M1 is the first starting torque; n e is the engine speed; β3 is the third correction coefficient.

[0033] Further, the second formula is:

[0034]

[0035] 0 < t3 < 1500

[0036] 0 < t b ≤ 10

[0037] 0 < t2 < 45

[0038] f9(t) = t2 + t b + t3

[0039] Wherein, f7(t) is the starting time of the boiler preheating; t2 is the second preheating time; t3 is the third preheating time; t b is the theoretical drag time of the engine when the boiler is preheating; P b is the electric power when the boiler is working; P air is the rated power of the preheating grid; P' s is the power of the starting motor when it just starts to drag and the fuel has not been combusted; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum electric quantity that can be used by the current vehicle during starting; J is the rotational inertia of the engine with the gearbox during starting; M2 is the second starting torque; n e is the engine speed; β3 is the third correction coefficient.

[0040] Further, after determining the first preheating time of the preheating grid before starting the engine, the preheating grid relay is closed, the preheating grid starts to preheat the intake air, the preheating grid preheating relay is closed after the preheating grid preheats for the first preheating time, the starting motor starts to drag the engine, the starting motor relay is disconnected when the engine speed reaches the set speed, the preheating grid relay is disconnected when the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

[0041] Further, after determining the second preheating time of the preheating grid and the third preheating time of the boiler before starting the engine, the boiler relay is first closed, the boiler starts to preheat, and the opening of the liquid heating pipeline proportional valve is adjusted to heat the engine and the gearbox; the preheating grid relay is closed after the boiler preheats for the third preheating time, the preheating grid starts to preheat the intake air, the starting motor relay is closed after the preheating grid preheats for the second preheating time, the starting motor starts to drag the engine, the starting motor relay is disconnected when the engine speed reaches the set speed, the preheating grid relay and the boiler relay are disconnected when the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

[0042] After the fourth preheating time of the preheating grid and the fifth preheating time of the boiler before starting the engine are determined, the boiler relay is closed first, the boiler starts preheating, and the opening of the liquid heating pipeline proportional valve is adjusted to heat the engine and the gearbox; after the fifth preheating time of the boiler, the preheating grid relay is closed, the preheating grid starts air preheating, the preheating grid preheating fourth preheating time, the starting motor relay is closed to start the engine, the engine speed reaches the set speed, the starting motor relay is disconnected, the preheating grid relay and the boiler relay are disconnected when the engine speed reaches the idle speed, and the vehicle low-temperature starting is successful.

[0043] Further, if the engine speed does not reach the set speed after the engine is continuously dragged for a set time, the starting motor relay is disconnected to stop dragging the engine.

[0044] After stopping dragging the engine, if the engine stops running, it is determined that the vehicle low-temperature starting fails, the number of consecutive failures of the vehicle low-temperature starting is recorded, and if the number of consecutive failures of the vehicle low-temperature starting reaches a set number, the vehicle is not started; otherwise, the current actual SOC value of the battery is determined.

[0045] After stopping dragging the engine, if the engine continues to run until the speed reaches the set speed, the preheating grid relay and the boiler relay are disconnected when the engine speed reaches the idle speed, and the vehicle low-temperature starting is successful.

[0046] Further, after the vehicle low-temperature starting is successful or the number of consecutive failures of the vehicle low-temperature starting reaches a set number, the correction coefficient after the vehicle starting is determined based on the actual parameters of the engine, the correction coefficient after the vehicle starting is compared with the correction coefficient before the vehicle starting, and it is determined whether the correction coefficient needs to be modified.

[0047] Further, the difference between the correction coefficient after the vehicle starting and the correction coefficient before the vehicle starting is calculated, if the absolute value of the difference is greater than a set threshold value and the absolute value of the average of the three consecutive differences is greater than a set threshold value, it is determined that the correction coefficient needs to be modified, and the average of the three consecutive differences is used to replace the current correction coefficient before the vehicle starting for parameter calculation when the next vehicle low-temperature starting is performed.

[0048] The beneficial effects of the present application are:

[0049] The application comprehensively considers the battery SOC value, starting temperature and other factors, selects whether to start the vehicle and the corresponding preheating strategy according to different situations, different preheating strategies correspond to different power distribution (preheating of the preheating grid and the boiler, and dragging of the motor will consume power, and each preheating time and dragging time corresponds to different power consumption), through reasonable distribution of power, over-discharge of the battery under low temperature or starting failure is avoided, the success rate of low-temperature starting of the vehicle is improved, and reasonable use of the battery power is considered, unnecessary energy consumption is avoided, and the service life of the battery is prolonged. The application significantly improves the reliability of vehicle starting in a low-temperature environment, reduces the starting difficulty problem caused by low temperature, reduces the starting time, improves the user experience, and ensures the normal use of the vehicle.

[0050] The application comprehensively considers the environmental temperature, engine coolant temperature, engine oil temperature and transmission oil temperature and other factors, avoids misjudgment of a single temperature parameter, reasonably distributes the influence of each factor on the starting temperature through the weight coefficient, more accurately reflects the actual working condition, and can more accurately judge the low-temperature starting condition of the vehicle, provides a more reliable basis for subsequent starting strategy making, and improves the effectiveness of the starting strategy.

[0051] The application combines the instantaneous battery power percentage when the vehicle is powered on, and the actual voltage, current and time of the battery during the period from the vehicle being powered on to the starting gear, and obtains a more accurate real-time battery power percentage through formula calculation, considers the dynamic change of the battery, provides a more accurate basis for determining whether to start the engine according to the battery power, and avoids starting failure or excessive use of the battery caused by inaccurate battery power judgment.

[0052] The application sets different SOC value thresholds, manages the starting process in different levels according to the SOC interval (low power alarm, medium power prompt and high power direct starting), and sends a warning to the driver to select when the power is insufficient, fully considers the battery power and the willingness of the driver, guarantees the low-temperature starting demand of the vehicle, effectively protects the battery, avoids starting failure or damage to the battery caused by too low battery power, and improves the informed right and control right of the driver on the vehicle state.

[0053] The application comprehensively considers the torque provided by the starting motor, the power torque provided by the fuel combustion and the resistance torque of the engine and the transmission, accurately calculates the starting torque through the formula, makes the calculation of the starting torque more scientific and reasonable, provides an accurate starting torque parameter for subsequent preheating time calculation, helps to make a more reasonable preheating strategy, and improves the success rate of low-temperature starting of the vehicle.

[0054] The present application adopts different formulas to calculate the shortest starting time according to whether the boiler is preheated or not, introduces parameters such as electric quantity, power, moment of inertia, etc. in the formulas, comprehensively covers the starting energy demand, and determines the preheating time according to the calculation result, adopts the set preheating time if there is no positive real solution, considers various situations, makes the determination of the preheating time more flexible and reliable, can reasonably allocate the preheating time according to different starting conditions and preheating modes, improves the preheating efficiency, ensures the engine to start under suitable conditions, and improves the starting success rate.

[0055] The present application determines the operation sequence of the boiler preheating, the preheating grid preheating, the starting motor dragging the engine and the engine speed reaching the idle speed, and simultaneously mentions adjusting the opening of the liquid heating pipeline proportional valve, so that the starting process is clearer and more standardized, the reliability and stability of the vehicle low-temperature starting are ensured, and the preheating effect and the starting success rate are improved.

[0056] The present application sets a processing mechanism that the engine speed does not reach the idle speed after the engine is continuously dragged for a set time, including stopping the dragging, recording the failure number and determining whether to start the vehicle according to the failure number, avoids endless dragging to cause damage to the engine and the battery, improves the safety of the vehicle low-temperature starting process, protects the engine and the battery, and helps to troubleshoot the starting problem through analyzing the failure number.

[0057] The present application compares the correction coefficient after the engine starts with the correction coefficient before the engine starts after the vehicle low-temperature starting is successful or continuously fails to reach a set number, determines whether the correction coefficient needs to be modified, so that the starting strategy can be dynamically adjusted according to the actual starting condition, improves the adaptability and accuracy of the starting strategy, helps to further optimize the vehicle low-temperature starting performance, and improves the starting success rate; and sets a modification condition of the correction coefficient, ensures that the modification of the correction coefficient is based on relatively stable starting data changes, avoids unnecessary modification caused by accidental factors, makes the modification of the correction coefficient more scientific and reasonable, ensures the stability and reliability of the starting strategy, and improves the overall performance of the vehicle low-temperature starting.

[0058] The various schemes of the vehicle low-temperature starting method based on the electric energy distribution cooperate with each other, optimize the vehicle low-temperature starting process from different aspects, improve the starting success rate, protect the battery and the engine, and improve the user experience and the overall performance of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 It is a system principle diagram of the present application.

[0060] Figure 2 It is a flowchart of the present application DETAILED DESCRIPTION

[0061] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0062] like Figure 1 The diagram shown illustrates the system principle of the vehicle low-temperature starting method based on power distribution according to the present invention. The system is centered around a control unit, which can be a standalone unit or part of an engine controller. Input signals include key signal, total battery current, ambient temperature, intake manifold temperature, engine coolant temperature, engine oil temperature, and transmission oil temperature. Output signals control the preheating grille, boiler, starter motor, proportional valve of the liquid heating pipeline, power input relays of other controllers, and display terminal lights. The display terminal uses CAN communication, and the proportional valve is controlled by PWM signals.

[0063] like Figure 2 As shown, the present invention provides a vehicle low-temperature starting method based on power distribution, comprising the following steps:

[0064] S1, when the vehicle is first powered on, the power supply to other controllers and control units is disconnected, and only the battery charge detection circuit is connected. Inside the control unit, there are large resistance and voltage measuring elements that can measure the battery voltage value (initial value). The control unit can determine the current instantaneous battery charge percentage (SOC′) based on the battery voltage value, battery aging correction, and the first correction coefficient (β1, initial value 1). After the calculation is completed, the circuit (battery charge detection circuit) is disconnected, and other power supplies are restored. The specific calculation process for SOC′ is as follows: Based on the [battery voltage value - actual SOC] curve, the actual SOC value corresponding to the battery voltage value can be found using the battery voltage value; based on the [battery usage time - aging correction coefficient] curve, the current aging correction coefficient can be found using the current battery usage time; then, the actual SOC value, the current aging correction coefficient, and the first correction coefficient are multiplied together to obtain the instantaneous battery charge percentage.

[0065] When the vehicle is in starter gear, the current real-time battery charge percentage is calculated based on the previously observed battery voltage and current. Wherein, SOC is the real-time battery charge percentage; V is the real-time battery voltage, obtained by measuring the battery input voltage inside the ECU; I is the real-time total battery current; and t is the time period from when the vehicle is powered on to when the vehicle is in starter gear.

[0066] It should be noted that the above vehicle power-on can be through the key power-on, or through the press of a one-key start button; the vehicle to the start gear is a step after the vehicle power-on, which can be through the operation signal of the key to the start gear, or through the operation signal of the button to the start gear.

[0067] S2, when the vehicle is to the start gear, the ambient temperature T is measured by the sensor arranged at the corresponding position e , the initial engine coolant temperature T w , the initial engine oil temperature T o , and the initial transmission oil temperature T t , and it is determined whether the corresponding measured value is normal, and the determination method is whether the measured value is within the set range, such as 50℃≥T e ≥-50℃, 120℃≥T w ≥-50℃, 140℃≥T o ≥-50℃, 110℃≥T t ≥-50℃, if a value exceeds the range (i.e. abnormal), the sensor fault will be prompted on the display terminal.

[0068] The starting temperature T is calculated according to the measured temperature, wherein A1, A2, A3, A4 are weight coefficients of the ambient temperature, the initial engine coolant temperature, the initial engine oil temperature, and the initial transmission oil temperature, respectively, and are calibration values, A1+A2+A3+A4=1, preferably, A1, A2, A3, A4 can be respectively taken as 20%, 20%, 30%, and 30%. If a measured value is abnormal, the starting temperature is recalculated, and the corresponding weight part is removed from the upper and lower parts of the formula, such as if the initial engine oil temperature test exceeds the corresponding set range, it indicates that the sensor at this position is faulty, and the detection result is inaccurate, then the parameters (including numerator and denominator) about the initial engine oil temperature in the starting temperature formula are all deleted, and the starting temperature is calculated by retaining other parameters.

[0069] After the starting temperature is calculated, it is compared with the temperature threshold value, if T≤temperature threshold value, it indicates that the current vehicle is in a low temperature environment, then the low temperature starting program is started, and step S3 is performed; otherwise (T>threshold value) the vehicle is directly started, and does not enter the low temperature starting (at this time, the temperature is relatively high, and there is no problem of low temperature starting).

[0070] S3, compare the real-time battery power percentage (SOC) calculated in step S1 with the first SOC set value (SOC1) and the second SOC set value (SOC2) to determine whether to start the vehicle: if SOC < SOC1, the intelligent terminal prompts that the battery power is low, displays the current SOC value and does not allow the vehicle to start, and the program ends; if SOC1≤SOC < SOC2, the intelligent terminal prompts a low power warning, displays the current SOC value and pops up a window to ask the driver whether to start the vehicle, if the driver selects yes, step S4 is entered, and if the driver selects no, the program ends; if SOC≥SOC2, step S4 is directly entered.

[0071] It should be noted that the above-mentioned SOC1 and SOC2 are both calibration values, and the specific size can be set according to actual needs, preferably, SOC1 is 5%, and SOC2 is 25%, that is, when the battery SOC is less than 5%, it means that the battery power is seriously low and the vehicle cannot be started, and the program ends directly, waiting for the battery to be charged or the power to be restored; when the battery SOC is between 5% and 25%, it means that the battery power is low and can barely meet the vehicle starting, but there is a problem of starting failure, at this time the right to choose is given to the driver to decide whether to start the vehicle, when the driver selects to start the vehicle, the subsequent step is performed, and when the driver does not select to start the vehicle, the program ends; when the battery SOC is greater than or equal to 25%, it means that the battery power is sufficient and the vehicle can be started directly in the subsequent step.

[0072] S4, if it is determined to start the vehicle in step S3, the starting torque M is calculated according to the information when the vehicle is in the starting gear, which is used for subsequent preheating time calculation. According to the different temperatures at different positions under the conditions of no boiler heating and boiler heating, the calculated results are respectively the first starting torque and the second starting torque, and the temperature values in different conditions are described below.

[0073] S4.1, calculate the starting torque M = M s + M e - M fe - M ft , M s is the torque provided by the starting motor, M e is the power torque provided by fuel combustion, M fe is the resistance torque of the engine, and M ft is the resistance torque of the gearbox.

[0074] S4.2, calculate the torque provided by the starting motor P s is the power of the starting motor; n e is the engine speed; and ε is the transmission efficiency from the starting motor to the crankshaft end, which is determined by mechanical design and written into the control unit in advance, and can generally be taken as 0.97.

[0075] S4.2.1, the power P of the starter motor s related to the starter motor speed n s , P s = f1(n s ), which is determined by the starter motor characteristic curve and written into the control unit in advance; the starter motor speed n s = Kn e ; K is the ratio of the starter motor speed to the engine speed, which is determined by mechanical design and written into the control unit in advance.

[0076] S4.3, calculating the power torque provided by fuel combustion ρ is the fuel density; m is the engine fuel injection amount; δ is the fuel combustion efficiency.

[0077] S4.3.1, ρ is related to the ambient temperature and the type of fuel, T e ≥ 5℃, diesel fuel is taken as 0.82 kg / L and gasoline is taken as 0.75 kg / L; 5℃ > T e ≥ -15℃, diesel fuel is taken as 0.83 kg / L and gasoline is taken as 0.76 kg / L; -15℃ > T e , diesel fuel is taken as 0.835 kg / L and gasoline is taken as 0.77 kg / L.

[0078] S4.3.2, m is related to the engine speed, m = f2(n e ), which is determined by the engine starting fuel injection curve and written into the control unit in advance.

[0079] S4.3.3, T′ W is the coolant temperature of the engine at the end of preheating, which is solved in the following step S5 to find the minimum starting time Minf7(t), and since there is no boiler preheating, T′ W = T w , and the corresponding starting torque is the first starting torque; in the following step S7, the corresponding T" w will be solved when the boiler is heated, and then T′ W = T" w , and the starting torque calculated therefrom is the second starting torque; γ is the combustion efficiency under standard conditions (ambient temperature at 25±2℃ and coolant temperature > 80℃), which is related to the engine speed n e and the fuel injection amount m, γ = f3(n e , m) is determined by test or simulation and written into the control unit in advance; T′ air is the air temperature of the intake manifold at the end of preheating, which is used in step S5 or which is used in step S8, T airT0 is the temperature of the intake manifold before preheating; L is the length of the intake pipe; r is the radius of the cross section of the intake pipe; p is the density of air air air = f4(T air ), which is a function of T air , written in advance into the control unit; t1 is the first preheating time; t2 is the second preheating time; P air is the rated power of the intake preheating grid; θ is the heating efficiency of the intake preheating grid, determined by test or simulation and written in advance into the control unit; β2 is the second correction coefficient, initially 1.

[0080] S4.4, calculate the resistance torque M fe = f5(T′ fe , n e ) of the engine, the resistance torque in the low-temperature starting stage of the engine being mainly the friction torque, the function being determined by the engine speed n e and the weighted temperature T′ fe , written in advance into the control unit according to the results of the motoring test during development;

[0081] T′ fe = 0.7T′ w + 0.3T′ O , T′ O being the oil temperature of the engine at the end of preheating, T′ O = T O when there is no boiler preheating, and T′ O = T″ O when there is boiler preheating.

[0082] S4.5, calculate the resistance torque M ft = f6(T′ t , n e ) of the automatic transmission, the resistance torque in the low-temperature starting stage of the transmission being mainly the friction torque, the function being determined by the engine speed n e and the oil temperature T′ t of the transmission at the end of preheating, written in advance into the control unit according to the results of the motoring test during development; T′ t = T t when there is no boiler preheating, and T′ t = T″ t when there is boiler preheating.

[0083] S5, calculate the shortest starting time Minf7(t) according to the formulas ①-⑤;

[0084]

[0085] 0 < t a ≤ 10 ………………………………………… ③​

[0086] 0≤t1≤45…………………………④

[0087] f7(t) = t1 + t a ………………………………⑤

[0088] Where f7(t) is the start-up time without boiler preheating, P′ s The power of the starter motor when it first starts driving the fuel before it burns is given by M. s =M fe +M ft The engine speed n′ at this moment (i.e., when the starter motor has just begun to drive the fuel but before it has burned) is calculated. e M s M fe M ft Calculate P′ using steps 4.2, 4.4, and 4.5 respectively, and then calculate P′ using step 4.2.1. s ; The starter motor power is calculated when the engine speed reaches 400 rpm; J is the moment of inertia of the engine and gearbox during the starting phase; M is calculated from 4.1; Q is the maximum amount of electricity expected to be available for starting the vehicle, Q = (SOC - 25%) * C20, where C20 is the battery capacity, t1 is the first preheating time, and t a β3 represents the theoretical engine drag time without boiler preheating; β3 is the third correction factor, initially set to 1.

[0089] S6. If the formula in step S5 has a positive real solution, then t1 and t2 are determined by Minf7(t). a The control unit outputs a command to close the preheating grille relay to start intake preheating, and the display terminal prompts that intake preheating has started. At the same time, the timer starts. When t1 is reached, the starter motor relay is closed to start driving the engine. The display terminal prompts that driving has started. When the engine speed reaches 400 rpm, the starter motor relay is disconnected. The preheating grille relay is disconnected when the engine speed continues to rise to idle speed. The vehicle starts successfully, and the starting phase ends.

[0090] S7. If the formula in step 5 has no positive real solution (indicating that boiler preheating needs to be started), then calculate the cold start for boiler preheating based on the information when the vehicle is in start gear, i.e., the boiler preheating time is t3; because of boiler heating, the engine coolant temperature T′ at the end of preheating in 4.3.3, 4.4 and 4.5 is... w Engine oil temperature T′ O and transmission fluid temperature T′ tf8 = f s - f5(T' fe , 400) + f6(T' t , 400) is the sum of engine resistance torque and gearbox resistance torque when the engine speed is 400 rpm, i.e. f8 = f w , T" O and T" t :

[0091] 0.0012(T" w - T w ) + 0.0005(T" o - T o ) + 0.0005(T" t - T t ) = t3P f αβ4

[0092]

[0093] T w < T" w … ⑧

[0094] T t < T" t … ⑨

[0095] P f is the power generated by the boiler combustion; α is the thermal efficiency of the liquid heating system when the boiler is combusting, determined by system test and written into the control unit in advance; N is the ratio of heat obtained by the engine coolant system and the engine oil, determined by system test and written into the control unit in advance; β4 is the fourth correction coefficient, initially 1.

[0096] S8, according to , find the shortest starting time Minf9(t);

[0097]

[0098] wherein P b is the electric power when the boiler is working; M2 is calculated from 4.1, wherein T' w , T' O and T' t are obtained from T" w , T" O and T" t calculated by S7.

[0099] It should be noted that t1, t2 and t3 in step S5 and step S8 correspond to the preheating time, which is not the actual preheating time of the corresponding device, but the action time of other devices after the corresponding device is preheated for the corresponding time, that is, t1 and t2 are the time from the start of preheating the grid to the closing of the motor relay, and after the time, the preheating grid continues to preheat until the preheating grid relay is disconnected; t3 is the time from the start of preheating the boiler to the start of preheating the grid, and after the time, the boiler continues to preheat until the boiler relay is disconnected.

[0100] S9, if the formula calculation in step S8 has a positive real solution, then t b , t2 and t3, t2 is the second preheating time, t b is the theoretical drag time of the engine when the boiler is preheated (i.e. the time from the closing of the motor relay to the opening of the motor relay in theory); t3 is the third preheating time; the control unit outputs an instruction to close the boiler relay, the boiler starts to work, and the display terminal prompts the start of boiler preheating, while adjusting the opening degree of the liquid heating pipeline proportional valve to heat the engine and the transmission, the opening degree of the proportional valve is obtained by dynamically adjusting the real-time detected engine coolant temperature T′′′ W and transmission oil temperature T′′′ t , the opening degree B of the proportional valve = 50 + (T′′′ w -T′′′ t ), B takes a value between 10 and 90, that is, if the calculated value exceeds the upper limit 90, the value is directly taken as 90, and if the calculated value is lower than the lower limit 10, the value is directly taken as 10; the heat of the boiler heating is partly for heating the engine and partly for heating the transmission, and the opening degree of the proportional valve corresponds to the part of the heat of the boiler heating supplied to the engine, that is, if B takes a value of 80, it means that the boiler heats 80% of the heat to the engine and 20% of the heat to the transmission; the boiler relay is closed to start timing, and when t3, the control unit outputs an instruction to close the preheating grid relay to start preheating the intake, the display terminal prompts the start of preheating the intake, and timing starts at the same time, and when t2, the starting motor relay is closed to start dragging the engine, the display terminal prompts the start of dragging, and the starting motor relay is opened when the engine speed reaches 400 rpm, and after the engine speed continuously rises to the idle speed, the preheating grid relay and the boiler relay are opened, the vehicle starts successfully, and the starting stage ends.

[0101] S10, if the formula calculation in step S8 has no positive real solution, then according to the calibrated preheating time (including the calibrated fourth preheating time and the fifth preheating time), the control unit outputs an instruction to close the boiler relay, the boiler starts to work, and the display terminal prompts the start of boiler preheating, while adjusting the opening degree of the liquid heating pipeline proportional valve, the opening degree of the proportional valve is obtained by dynamically adjusting the real-time detected engine coolant temperature T′′′ w and transmission oil temperature T′′′t Dynamic adjustment, the opening degree of proportional valve B = 50 (T w -T t ), B value between 10 to 90, unit is %, that is, if the calculated value exceeds the upper limit of 90, directly take the value of 90, if the calculated value is lower than the lower limit of 10, directly take the value of 10; the boiler relay is closed to start timing, to the fifth preheating time (such as 1500s) control unit output instruction to close the preheating grid relay to start preheating intake, display terminal prompts the start of preheating intake, and start timing, to the fourth preheating time (such as 45s) to close the starting motor relay to start dragging the engine, the display terminal prompts the start of dragging, the engine speed to the set speed (400 rpm) to disconnect the starting motor relay, the engine speed to idle speed, disconnect the preheating grid relay and the boiler relay, the vehicle starts successfully, the starting stage ends.

[0102] S11, in the above steps S6, S9, S10, if the engine is continuously dragged and the engine speed does not reach the set speed, but the dragging time reaches the set time, the starting motor relay is disconnected and the engine is stopped;

[0103] After stopping the dragging engine, if the engine stops running, it is determined that the vehicle fails to start at low temperature, the number of consecutive failures of the vehicle starting at low temperature is recorded, and if the number of consecutive failures of the vehicle starting at low temperature reaches the set number, the vehicle is not started; otherwise, return to step S1 to start again;

[0104] After stopping the dragging engine, in a small number of cases, the engine will continue to run, if the engine continues to run to the set speed, the preheating grid relay and the boiler relay are disconnected after the engine speed continues to rise to idle speed, and the vehicle starts successfully at low temperature.

[0105] It should be noted that during the dragging of the engine, under normal circumstances, the engine speed can reach the set speed before the set time, and the starting motor relay can be disconnected, and the vehicle can start successfully. The time from the start of dragging to the disconnection of the starting motor relay is the actual dragging time of the engine; when the battery power is insufficient or other equipment fails, the engine will be dragged until the set time and the engine speed still does not reach the set speed, then the dragging is stopped. The set time is the upper limit time for the starting motor to drag the engine, which is determined according to actual needs, preferably 45s, and the set number is generally 2.

[0106] S12. In each cycle, if the vehicle starts successfully in steps S6, S9, and S10, or if the number of consecutive low-temperature start failures in step S11 reaches the set number, it is necessary to determine whether to modify the corresponding correction coefficients (i.e., β1, β2, β3, and β4 mentioned above) based on the corresponding parameters. Specifically, the correction coefficients after the vehicle starts are determined based on the actual engine parameters or battery parameters. The correction coefficients after the vehicle starts (successfully or unsuccessfully) are compared with the correction coefficients before the vehicle starts, and the result of the comparison determines whether the correction coefficients need to be modified. The correction coefficients before the vehicle starts are all known values, either calibration values ​​or values ​​determined (modified) after the last start.

[0107] The specific process for determining the correction factor after vehicle start-up is as follows: Based on the actual air temperature in the engine intake manifold after vehicle start-up, the correction factor is determined using the formula described in section 4.3.3 above (i.e., replacing T′ in the formula with the actual air temperature). air β2 can be calculated after the vehicle starts. Based on the actual engine drag time (i.e., the actual time from the starter motor relay closing to opening), it can be calculated using the above formula ② or (that is, replace t in the formula with the actual drag time) a or t b This allows for the calculation of β3 after engine start-up. It is based on the actual engine coolant temperature T″′ measured after vehicle start-up. w Engine oil temperature T″′ O and transmission fluid temperature T″′ t By using the above formula ⑥ (i.e., replacing T in the formula with the actual detected value) w 、T″ O and T″ t The system can calculate β4 after vehicle startup. β1 is determined based on the battery charge. If the battery is fully charged after vehicle startup, β1 after startup is calculated by reverse engineering the SOC calculation process in S1. At this point, the SOC is 100%, meaning that... Determine SOC′, and then determine β1 based on SOC′; if the battery is not fully charged after the vehicle starts, then determine that β1 after the vehicle starts is equal to β1 before the vehicle starts.

[0108] The process of determining whether the correction factor needs to be modified based on the comparison results is as follows: Calculate the difference β between the correction factor after vehicle start-up and the correction factor before vehicle start-up. x That is, corresponding to β x The differences are denoted as follows: (x = 1, 2, 3, or 4 correspond to β1, β2, β3, and β4 respectively). If the absolute value of the difference of three consecutive values ​​of a certain correction coefficient is greater than a set threshold (i.e., three consecutive values), And the absolute value of the average of the differences of three consecutive times is greater than a set threshold (i.e.) If the average value of the difference of the three consecutive times is greater than the threshold value (T), it is determined that the corresponding correction coefficient needs to be modified to replace the correction coefficient before the current engine start with the average value of the difference of the three consecutive times for the parameter calculation when the vehicle is started next time at low temperature.

[0109] It should be understood that the particular order or hierarchy of steps in processes disclosed is merely illustrative. Based upon design preferences, it should be understood that the particular order or hierarchy of steps in the processes can be rearranged, so as to retain functionality of the corresponding step energies. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

[0110] In order to make the description of the present disclosure more detailed and complete, the above describes the illustrative description for the embodiments and specific examples of the present application; but this is not the only form of implementation or use of the specific embodiments of the present application. The embodiments include the features of the specific embodiments and the method steps and their order for constructing and operating these specific embodiments. However, other specific embodiments can also be used to achieve the same or equivalent functions and step orders.

[0111] In the above detailed description, various features are grouped together in a single embodiment for the sake of streamlining the disclosure. This disclosure of a feature together with other features does not imply that the described feature is required for every embodiment of the claimed subject matter. Rather, the application is subject to appended claims, which affirm only the specific features present in the specific embodiments. Thus, various claims can affirm respective ones of the specific embodiments, without the features not affirmed thereby being implied as necessary for every claim. In the claims, means-plus-function clauses are used where for clarity. In particular, any means-plus-function claim is intended to cover the structures described herein as performing the recited functionality, and not only structural equivalents but also equivalent structures. Covering the equivalent structures permits the patent claims to be drawn to potentially broadest scope of equivalents, without restricting the claim application of those elements otherwise known to be equivalents of claim limitations. Furthermore, structures that are why are equivalent to claim limitations are legally and equivalently considered to be covered by the claim, notwithstanding being an equivalent. The claim encompasses both the means-plus-function claim limitations and the equivalent structure.

[0112] In the above detailed description, various features are grouped together in a single embodiment for the sake of streamlining the disclosure. This disclosure of a feature together with other features does not imply that the described feature is required for every embodiment of the claimed subject matter. Rather, the application is subject to appended claims, which affirm only the specific features present in the specific embodiments. Thus, various claims can affirm respective ones of the specific embodiments, without the features not affirmed thereby being implied as necessary for every claim. In the claims, means-plus-function clauses are used where for clarity. In particular, any means-plus-function claim is intended to cover the structures described herein as performing the recited functionality, and not only structural equivalents but also equivalent structures. Covering the equivalent structures permits the patent claims to be drawn to potentially broadest scope of equivalents, without restricting the claim application of those elements otherwise known to be equivalents of claim limitations. Furthermore, structures that are why are equivalent to claim limitations are legally and equivalently considered to be covered by the claim, notwithstanding being an equivalent. The claim encompasses both the means-plus-function claim limitations and the equivalent structure.

[0113] The above merely shows specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered by the protection scope of the present application. The contents not described in detail in the specification belong to the prior art known by the person skilled in the art.

Claims

1. A vehicle low-temperature starting method based on power distribution, characterized in that: determining the current real-time battery power percentage and the starting temperature when the vehicle is shifted to the starting gear, and determining whether to start the vehicle according to the real-time battery power percentage if the starting temperature is lower than the temperature threshold; if it is determined to start the vehicle, calculating a first starting torque without boiler preheating, determining a first preheating time of the preheating grid before the engine starts based on the first starting torque; or calculating a second starting torque with boiler preheating, determining a second preheating time of the preheating grid and a third preheating time of the boiler before the engine starts based on the second starting torque, or determining a fourth preheating time of the preheating grid and a fifth preheating time of the boiler before the engine starts based on the second starting torque; calculating the shortest starting time without boiler preheating based on a first formula containing the first starting torque, and determining the first preheating time of the preheating grid before the engine starts based on the positive real solution if there is a positive real solution; if there is no positive real solution, it is determined to start the boiler preheating, the second starting torque with boiler preheating is calculated, and the shortest starting time with boiler preheating is calculated based on a second formula containing the second starting torque; if there is a positive real solution, the second preheating time of the preheating grid and the third preheating time of the boiler before the engine starts are determined based on the positive real solution; if there is no positive real solution, the fourth preheating time of the preheating grid and the fifth preheating time of the boiler before the engine starts are determined based on the calibration preheating time; controlling the preheating grid intake preheating for the first preheating time, or controlling the preheating grid intake preheating for the second preheating time and the boiler preheating for the third preheating time, or controlling the preheating grid intake preheating for the fourth preheating time and the boiler preheating for the fifth preheating time; after the preheating time reaches, the starting motor relay is closed to start the engine, and after the engine speed reaches the idle speed, the vehicle low-temperature starting is successful. The starting temperature is determined by the following formula:

2. The vehicle cold cranking method based on electric energy distribution according to claim 1, characterized in that, The determination process of the real-time battery power percentage is as follows: ； Wherein, T is the starting temperature; T e is the ambient temperature; T w is the initial engine coolant temperature; T o is the initial engine oil temperature; T t is the initial transmission oil temperature; A1, A2, A3, A4 are weight coefficients of the ambient temperature, the initial engine coolant temperature, the initial engine oil temperature, and the initial transmission oil temperature, respectively, and A1+A2+A3+A4=1.

3. The electric energy distribution based vehicle cold start method of claim 1, wherein, When the vehicle is powered on, the instantaneous battery power percentage when the vehicle is powered on is determined according to the battery voltage value, the battery aging correction coefficient and the first correction coefficient; The real-time battery power percentage is calculated by the formula according to the instantaneous battery power percentage, Wherein, SOC is the real-time battery power percentage; SOC' is the instantaneous battery power percentage; V is the real-time voltage of the battery; I is the real-time total current of the battery; t is the time period between the time when the vehicle is powered on and the time when the vehicle is shifted to the starting gear. ； The determination whether to start the vehicle according to the real-time battery power percentage includes:

4. The electric energy distribution based vehicle cold start method of claim 1, wherein, If the real-time battery power percentage is less than the first SOC set value, the vehicle is not started; If the real-time battery power percentage is greater than or equal to the first SOC set value and less than the second SOC set value, an alarm is issued that the battery power is low, and a pop-up window prompts the driver to select whether to start the vehicle; If the real-time battery power percentage is greater than or equal to the second SOC set value, it is directly determined to start the vehicle. The first starting torque or the second starting torque is determined by the following formula:

5. The electric energy distribution based vehicle cold start method of claim 1, wherein, The first formula is: M = M s +M e -M fe -M ft； Wherein, M is the starting torque; M s Torque provided by the starting motor; M e Torque provided by the fuel combustion; M fe Torque provided by the engine resistance; M ft Torque provided by the transmission resistance.

6. The electric energy distribution based vehicle cold start method of claim 1, wherein, The second formula is: ； Wherein, f7(t) is the starting time without boiler preheating; t1 is the first preheating time; t a is the theoretical drag time of the engine without boiler preheating; P air is the rated power of the preheating grid; is the power of the starting motor when it just starts to drag and the fuel has not been burned; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum power that can be used for the current vehicle starting; J is the rotational inertia of the engine with the gearbox during the starting stage; M1 is the first starting torque; n e is the engine speed; β3 is the third correction coefficient.

7. The electric energy distribution based vehicle cold start method of claim 1, wherein, ​ ； Wherein, f9(t) is the starting time of the boiler preheating; t2 is the second preheating time; t3 is the third preheating time; t b is the theoretical drag time of the engine for the boiler preheating; b is the electric power when the boiler works; air is the rated power of the preheating grid; is the power of the starting motor when the starting motor just starts to drag and the fuel has not been combusted; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum electric quantity that can be used by the current vehicle during starting; J is the rotational inertia of the engine with the gearbox during starting; M2 is the second starting torque; n e is the engine speed; β3 is the third correction coefficient.

8. The electric energy distribution based vehicle cold cranking method of claim 1, wherein: After determining the first preheating time of the preheating grid before starting the engine, the preheating grid relay is closed, the preheating grid starts to preheat the intake air, the starting motor relay is closed after the preheating grid preheats for the first preheating time to start dragging the engine, the starting motor relay is opened when the engine speed reaches the set speed, the preheating grid relay is opened when the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

9. The electric energy distribution based vehicle cold cranking method of claim 1, wherein: After determining the second preheating time of the preheating grid and the third preheating time of the boiler before starting the engine, the boiler relay is first closed, the boiler starts to preheat, and the opening of the liquid heating pipeline proportional valve is adjusted to heat the engine and the transmission; the preheating grid relay is closed after the boiler preheats for the third preheating time, the preheating grid starts to preheat the intake air, the starting motor relay is closed after the preheating grid preheats for the second preheating time to start dragging the engine, the starting motor relay is opened when the engine speed reaches the set speed, the preheating grid relay and the boiler relay are opened when the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

10. A vehicle cold start method based on electrical energy distribution according to claim 8 or 9, characterized in that: If the engine speed does not reach the set speed after continuously dragging the engine for a set time, the starting motor relay is opened to stop dragging the engine; After stopping dragging the engine, if the engine stops running, it is determined that the vehicle fails to start at low temperature, the number of consecutive failures of the vehicle starting at low temperature is recorded, and if the number of consecutive failures of the vehicle starting at low temperature reaches a set number, the vehicle is not started; otherwise, the current actual SOC value of the battery is determined. After stopping dragging the engine, if the engine continues to run until the speed reaches the set speed, the preheating grid relay and the boiler relay are opened when the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

11. The method of claim 10, wherein the method is based on electrical energy distribution for vehicle cold start. After the vehicle is successfully started at low temperature or the number of consecutive failures of the vehicle starting at low temperature reaches a set number, the correction coefficient after the vehicle is started is determined based on the actual parameters of the engine, the correction coefficient after the vehicle is started is compared with the correction coefficient before the vehicle is started, and it is determined whether the correction coefficient needs to be modified.

12. The method of claim 11, wherein: The difference between the correction coefficient after the vehicle is started and the correction coefficient before the vehicle is started is calculated, if the absolute value of the difference is greater than a set threshold value for three consecutive times and the absolute value of the average of the three consecutive differences is greater than a set threshold value, it is determined that the correction coefficient needs to be modified, and the average of the three consecutive differences is used to replace the current correction coefficient before the vehicle is started for parameter calculation when the vehicle is started at low temperature next time.

Images