Vehicle low-temperature starting method based on electric energy distribution

Abstract

The invention discloses a vehicle low-temperature starting method based on electric energy distribution, which comprises the following steps: when a vehicle reaches a starting gear, determining the current real-time battery electric quantity percentage and judging the starting temperature, and if the starting temperature is lower than a temperature threshold, determining whether to start the vehicle according to the real-time battery electric quantity percentage; if it is determined that the vehicle is started, the first preheating time of a preheating grid before the engine is started is determined, or the second preheating time of the preheating grid before the engine is started and the third preheating time of a boiler are determined; controlling the first preheating time of intake preheating of the preheating grid, or controlling the second preheating time of intake preheating of the preheating grid and the third preheating time of boiler preheating; and after the preheating time is up, a starting motor relay is closed to start dragging the engine, and the vehicle is successfully started at low temperature after the rotating speed of the engine reaches the idle speed. According to the invention, the starting reliability of the vehicle in a low-temperature environment is obviously improved, the problem of starting difficulty caused by low temperature is reduced, the user experience is improved, and the normal use of the vehicle is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control, and particularly relates to a method for starting a vehicle at low temperature based on power distribution. Background Art

[0002] Currently, automatic transmissions are becoming more and more popular. After a vehicle is equipped with an automatic transmission, since the engine cannot be completely disengaged from the transmission through the clutch, starting at low temperature is more difficult, and auxiliary technical means such as intake preheating and boiler heating need to be added, resulting in a long starting time and complex operation.

[0003] Currently, for starting an engine at low temperature, methods such as heating the engine coolant and intake heating are adopted to realize coolant circulation heating and intake heating for multiple cylinders of the engine simultaneously, so that the engine can be quickly started in an extremely cold environment in a short time. The starting conditions of this method do not consider the battery power factor, which may lead to starting failure due to low power, and do not judge the starting resistance at different temperatures, increasing the risk of starting failure. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies existing in the above background art and provide a method for starting a vehicle at low temperature based on power distribution.

[0005] The technical solution adopted by the present invention is: a method for starting a vehicle at low temperature based on power distribution. When the vehicle is in the start gear, determine the current real-time battery power percentage and judge the starting temperature. If the starting temperature is lower than the temperature threshold, determine whether to start the vehicle according to the real-time battery power percentage;

[0006] If it is determined to start the vehicle, calculate the first starting torque without boiler preheating, and determine the first preheating time of the preheating grille before engine starting based on the first starting torque; or calculate the second starting torque with boiler preheating, and determine the second preheating time of the preheating grille before engine starting and the third preheating time of the boiler based on the second starting torque, or determine the fourth preheating time of the preheating grille before engine starting and the fifth preheating time of the boiler based on the second starting torque;

[0007] Control the preheating grille to intake air and preheat for the first preheating time, or control the preheating grille to intake air and preheat for the second preheating time and the boiler to preheat for the third preheating time, or control the preheating grille to intake air and preheat for the fourth preheating time and the boiler to preheat for the fifth preheating time;

[0008] After the preheating time is reached, close the starting motor relay to start dragging the engine. When the engine speed reaches the idle speed, the vehicle starts successfully at low temperature.

[0009] Furthermore, 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, and 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] Furthermore, the determination process of the real-time battery charge percentage is as follows:

[0013] When the vehicle is powered on, determine the instantaneous battery charge percentage at the time of vehicle power-on according to the battery voltage value, the battery aging correction coefficient, and the first correction coefficient;

[0014] Calculate the real-time battery charge percentage through a formula based on the instantaneous battery charge percentage,

[0015]

[0016] wherein, SOC is the real-time battery charge percentage; SOC′ is the instantaneous battery charge percentage; V is the real-time battery voltage; I is the real-time total battery current; t is the time period between the vehicle power-on moment and the vehicle reaching the start gear moment.

[0017] Furthermore, determining whether to start the vehicle according to the real-time battery charge percentage includes:

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

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

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

[0021] Furthermore, 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 driving torque provided for fuel combustion; M fe The resistance torque of the engine; M ft The resistance torque of the transmission.

[0024] Further, determining the first preheating time of the preheating grille before engine starting based on the first starting torque, or determining the second preheating time of the preheating grille before engine starting and the third preheating time of the boiler based on the second starting torque, or determining the fourth preheating time of the preheating grille before engine starting and the fifth preheating time of the boiler based on the second starting torque, includes:

[0025] Based on a first formula including the first starting torque, calculate the shortest starting time without preheating the boiler. If the calculation result has a positive real solution, determine the first preheating time of the preheating grille before engine starting based on the positive real solution; if the calculation result has no positive real solution, calculate the shortest starting time with preheating the boiler based on a second formula including the second starting torque;

[0026] If the calculation result has a positive real solution, determine the second preheating time of the preheating grille before engine starting and the third preheating time of the boiler based on the positive real solution; if the calculation result has no positive real solution, determine the fourth preheating time of the preheating grille before engine starting and the fifth preheating time of the boiler based on the calibrated preheating time.

[0027] Further, the first formula is:

[0028]

[0029] 0 < t a ≤ 10

[0030] 0 ≤ t 1 ≤ 45

[0031] f 7 (t) = t 1 + t a

[0032] where, f 7 (t) is the starting time without preheating the boiler; t 1 is the first preheating time; t a is the theoretical driving time of the engine without preheating the boiler; P air is the rated power of the preheating grille; P s ′ is the power of the starting motor when it just starts to drive and the fuel has not burned yet; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum available power for the current vehicle starting; J is the moment of inertia of the engine with the transmission during the starting stage; M 1 is the first starting torque; n eis the engine speed; β 3 is the third correction coefficient.

[0033] Further, the second formula is:

[0034]

[0035] 0 < t 3 ≤ 1500

[0036] 0 < t b ≤ 10

[0037] 0 < t 2 ≤ 45

[0038] f 9 (t) = t 2 + t b + t 3

[0039] where f 7 (t) is the starting time for preheating the boiler; t 2 is the second preheating time; t 3 is the third preheating time; t b is the theoretical driving time of the engine when preheating the boiler; 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 drive and the fuel has not burned yet; is the power of the starting motor when the engine speed reaches 400 rpm; Q is the maximum available electric quantity for the current vehicle starting; J is the moment of inertia of the engine with the gearbox during the starting stage; M 2 is the second starting torque; n e is the engine speed; β 3 is the third correction coefficient.

[0040] Further, after determining the first preheating time of the preheating grid before engine starting, close the preheating grid relay, and the preheating grid starts to intake and preheat. After the preheating grid preheats for the first preheating time, close the starting motor relay to start driving the engine. After the engine speed reaches the set speed, disconnect the starting motor relay. After the engine speed reaches the idle speed, disconnect the preheating grid relay, and the vehicle cold start is successful.

[0041] Further, after determining the second preheating time of the preheating grille before engine starting and the third preheating time of the boiler, first close the boiler relay, and the boiler starts preheating. At the same time, adjust the opening of the proportional valve of the liquid heating pipeline to heat the engine and the transmission; after the boiler preheats for the third preheating time, close the preheating grille relay, and the preheating grille starts intake air preheating. After the preheating grille preheats for the second preheating time, close the starting motor relay to start dragging the engine. After the engine speed reaches the set speed, disconnect the starting motor relay. After the engine speed reaches the idle speed, disconnect the preheating grille relay and the boiler relay, and the vehicle's low-temperature starting is successful.

[0042] After determining the fourth preheating time of the preheating grille before engine starting and the fifth preheating time of the boiler, first close the boiler relay, and the boiler starts preheating. At the same time, adjust the opening of the proportional valve of the liquid heating pipeline to heat the engine and the transmission; after the boiler preheats for the fifth preheating time, close the preheating grille relay, and the preheating grille starts intake air preheating. After the preheating grille preheats for the fourth preheating time, close the starting motor relay to start dragging the engine. After the engine speed reaches the set speed, disconnect the starting motor relay. After the engine speed reaches the idle speed, disconnect the preheating grille relay and the boiler relay, and the vehicle's low-temperature starting is successful.

[0043] Further, if the engine speed does not reach the set speed after continuously dragging the engine for the set time, then disconnect the starting motor relay to stop dragging the engine;

[0044] After stopping dragging the engine, if the engine stops running, then determine that the vehicle's low-temperature starting fails, record the number of consecutive failures of the vehicle's low-temperature starting. If the number of consecutive failures of the vehicle's low-temperature starting reaches the set number, then do not start the vehicle; otherwise, return to determine the current actual SOC value of the battery;

[0045] After stopping dragging the engine, if the engine continues to run until the speed reaches the set speed, then after the engine speed reaches the idle speed, disconnect the preheating grille relay and the boiler relay, and the vehicle's low-temperature starting is successful.

[0046] Further, after the vehicle's low-temperature starting is successful or the number of consecutive failures of the vehicle's low-temperature starting reaches the set number, determine the correction coefficient after vehicle starting based on the actual parameters of the engine, compare the correction coefficient after vehicle starting with the correction coefficient before vehicle starting, and determine whether to modify the correction coefficient.

[0047] Even further, calculate the difference between the correction coefficient after vehicle starting and the correction coefficient before vehicle starting. If the absolute value of the difference for three consecutive times is greater than the set threshold and the absolute value of the average of the differences for three consecutive times is greater than the set threshold, then determine that the correction coefficient needs to be modified, and replace the current correction coefficient before vehicle starting with the average of the differences for three consecutive times for parameter calculation during the next vehicle low-temperature starting.

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

[0049] The present invention comprehensively considers factors such as the battery SOC value and the starting temperature, and selects whether to start the vehicle and the corresponding preheating strategy according to different situations. Different preheating strategies correspond to different power distribution (the preheating of the preheating grid and the boiler, and the dragging of the motor will consume power, and each determined preheating time and dragging time correspond to different power consumption). By reasonably allocating power, over-discharge of the battery or starting failure at low temperatures is avoided, and the success rate of low-temperature starting of the vehicle is improved. At the same time, the reasonable use of battery power is taken into account, unnecessary energy consumption is avoided, and the battery service life is extended. The present invention significantly improves the reliability of vehicle starting in a low-temperature environment, reduces the problem of starting difficulties caused by low temperatures, reduces the starting time, improves the user experience, and ensures the normal use of the vehicle.

[0050] The present invention comprehensively considers multiple factors such as ambient temperature, engine coolant temperature, engine oil temperature and transmission oil temperature to avoid misjudgment of a single temperature parameter, and reasonably distributes the influence of various factors on the starting temperature through weight coefficients, so as to more accurately reflect the actual working conditions and more accurately judge the low-temperature starting conditions of the vehicle, thereby providing a more reliable basis for the subsequent formulation of the starting strategy and improving the effectiveness of the starting strategy.

[0051] The present invention 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 vehicle power-on to the starting gear, and obtains a more accurate real-time battery power percentage through a formula calculation, taking into account the dynamic changes of the battery, and providing a more accurate basis for determining whether to start the engine according to the battery power, thereby avoiding starting failure or battery overuse problems caused by inaccurate battery power judgment.

[0052] The present invention sets different SOC value thresholds, manages the starting process in a hierarchical manner according to the SOC intervals (low battery warning, medium battery prompt, high battery direct start), and issues an alarm to prompt the driver to make a choice when the battery is insufficient. The present invention fully considers the battery power and the driver's wishes, and effectively protects the battery while ensuring the vehicle's low-temperature starting requirements, avoiding starting failure or battery damage due to low battery power, and also improves the driver's right to know and control the vehicle status.

[0053] The present invention comprehensively considers the torque provided by the starter motor, the power torque provided by the fuel combustion, and the resistance torque of the engine and the gearbox, and accurately calculates the starting torque through a formula, so that the calculation of the starting torque is more scientific and reasonable, and provides accurate starting torque parameters for subsequent preheating time calculation, which is helpful to formulate a more reasonable preheating strategy and improve the success rate of low-temperature starting of the vehicle.

[0054] The present invention calculates the shortest starting time using different formulas according to whether boiler preheating is carried out. Parameters such as electric quantity, power, and moment of inertia are introduced into the formulas to comprehensively cover the starting energy requirements. The preheating time is determined based on the calculation results. If there is no positive real solution in the calculation results, a set preheating time is adopted. Considering various situations, the determination of the preheating time is made more flexible and reliable. It can reasonably allocate the preheating time according to different starting conditions and preheating methods, improve the preheating efficiency, ensure the engine starts under suitable conditions, and increase the starting success rate.

[0055] The present invention clarifies the operation sequence of boiler preheating, preheating grille preheating, starting motor dragging the engine, and the operations after the engine speed reaches idle speed. At the same time, it mentions adjusting the opening degree of the proportional valve of the liquid heating pipeline, making the starting process clearer and more standardized, ensuring the reliability and stability of vehicle low-temperature starting, improving the preheating effect and starting success rate.

[0056] The present invention sets up a processing mechanism for the situation where the engine speed does not reach idle speed after continuously dragging for a set time, including stopping dragging, recording the failure times, and deciding whether to start the vehicle according to the failure times. This avoids damage to the engine and battery caused by endless dragging, improves the safety of the vehicle low-temperature starting process, protects the engine and battery, and helps to troubleshoot starting problems by analyzing the failure times.

[0057] After the vehicle low-temperature starting is successful or the continuous failure reaches the set number of times, the present invention determines whether to modify the correction coefficient by comparing the correction coefficient after the engine starts with the correction coefficient before starting. This enables the starting strategy to be dynamically adjusted according to the actual starting situation, improves the adaptability and accuracy of the starting strategy, helps to further optimize the vehicle low-temperature starting performance and increase the starting success rate. And it sets the modification conditions of the correction coefficient to ensure that the modification of the correction coefficient is based on relatively stable changes in starting data, avoiding unnecessary modifications caused by accidental factors, making the modification of the correction coefficient more scientific and reasonable, ensuring the stability and reliability of the starting strategy, and improving the overall performance of vehicle low-temperature starting.

[0058] Each solution of the vehicle low-temperature starting method based on electric energy distribution of the present invention cooperates with each other, optimizes the vehicle low-temperature starting process from different aspects, increases the starting success rate, protects the battery and the engine, and improves the user experience and the overall performance of the vehicle. Brief Description of the Drawings

[0059] Figure 1 is the system schematic diagram of the present invention.

[0060] Figure 2 is the flow chart of the present invention Detailed Embodiments

[0061] The following further describes the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not limit the present invention. In addition, 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] As Figure 1 shown, it is a system schematic diagram for implementing the vehicle low-temperature starting method based on electric energy distribution of the present invention. The system is centered around a control unit, which can be separate or part of an engine controller. The input signals include key signal, total battery current, ambient temperature, intake pipe temperature, engine coolant temperature, engine oil temperature, transmission oil temperature, etc.; the output signal controls include preheating grille, boiler, starting motor, liquid heating pipeline proportional valve, power input relay for other controllers, and display terminal lamp. Among them, the display terminal is communicated via CAN line, and the proportional valve is controlled by PWM signal.

[0063] As Figure 2 shown, a vehicle low-temperature starting method based on electric energy distribution provided by the present invention includes the following steps:

[0064] S1, when the vehicle is just powered on, the power supply to other controllers and other components of the control unit is disconnected, and only the battery power detection circuit is turned on. There are relatively large resistors and voltage measurement elements inside the control unit that can measure the battery voltage value (initial value). The control unit can determine the current instantaneous battery charge percentage (i.e., SOC′) according to the battery voltage value, battery aging correction, and the first correction coefficient (i.e., β 1 , with an initial value of 1), and after the calculation is completed, this circuit (battery power detection circuit) is disconnected, and other power supplies are restored. Among them, the specific calculation process of SOC′ is as follows: According to the [battery voltage value - actual SOC] curve, the actual SOC value corresponding to the battery voltage value can be found through the battery voltage value; according to the [battery usage time - aging correction coefficient] curve, the current aging correction coefficient can be found through the current battery usage time; then multiply the actual SOC value, the current aging correction coefficient, and the first correction coefficient to obtain the instantaneous battery charge percentage.

[0065] When the vehicle reaches the start gear, calculate the current real-time battery charge percentage of the battery according to the previous continuous battery voltage and current, wherein, SOC is the real-time battery charge percentage; V is the real-time battery voltage, obtained by measuring the voltage input by the battery inside the ECU, I is the real-time total battery current; t is the time period from the moment when the vehicle is powered on to the moment when the vehicle reaches the start gear.

[0066] It should be noted that the above-mentioned vehicle power-on can be achieved by turning on the power with a key or by pressing a one-key start button; the vehicle reaching the start gear is a step after the vehicle is powered on, which can be achieved by the operation signal of the key reaching the start gear or by the operation signal of a button, etc. reaching the start gear.

[0067] S2. When the vehicle reaches the start gear, measure the ambient temperature T with a 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 determine whether the corresponding measured values are normal. The determination method is whether the measured values are within the set range. For example, 50°C ≥ T e ≥ -50°C, 120°C ≥ T w ≥ -50°C, 140°C ≥ T o ≥ -50°C, 110°C ≥ T t ≥ -50°C. If a certain value exceeds the range (i.e., is abnormal), the sensor failure will be prompted on the display terminal.

[0068] Calculate the starting temperature T based on the measured temperature, where A1, A2, A3, and 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, which are calibration values, and A1 + A2 + A3 + A4 = 1. Preferably, A1, A2, A3, and A4 can be respectively set to 20%, 20%, 30%, and 30%. If a certain measured value is abnormal, recalculate the starting temperature, and remove the corresponding weight part from both the numerator and denominator of the formula. If the initial engine oil temperature test exceeds the corresponding set range, it indicates that the sensor at this position fails and the detection result is inaccurate. Then, delete the parameters (including the numerator and denominator) related to the initial engine oil temperature in the starting temperature formula, and retain other parameters to recalculate the starting temperature.

[0069] After calculating the starting temperature, compare it with the temperature threshold. If T ≤ the temperature threshold, it means that the current vehicle is in a low-temperature environment, then start the low-temperature starting program and proceed to step S3; otherwise (T > the threshold), directly start the vehicle without entering 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 ends the program; If SOC1 ≤ SOC < SOC2, the intelligent terminal prompts a low power alarm, displays the current SOC value and pops up a window for the driver to choose whether to start the vehicle. If the driver chooses yes, go to step S4; if the driver chooses no, end the program; If SOC ≥ SOC2, directly go to step S4.

[0071] It should be noted that both the above SOC1 and SOC2 are calibration values, and their specific sizes can be set according to actual needs. Preferably, the value of SOC1 is 5%, and the value of SOC2 is 25%. That is, when the battery SOC is less than 5%, it means that the battery power is seriously low and no longer supports the vehicle to start. Just end and wait for the battery to charge or the power to recover; When the battery SOC is between 5% and 25%, it means that the battery power is low and barely meets the vehicle start, but there is a problem of starting failure. At this time, the choice is left to the driver to decide whether to start the vehicle. When the driver chooses to start the vehicle, proceed to the subsequent steps. When the driver does not choose to start the vehicle, end the program; When the battery SOC is greater than or equal to 25%, it means that the battery power is sufficient and the vehicle can be directly started in the subsequent steps.

[0072] S4. If it is determined to start the vehicle in step S3, calculate the starting torque M according to the information when the vehicle reaches the starting gear for subsequent preheating time calculation. According to the different temperatures at different positions in the two cases of without boiler heating and with boiler heating, the calculated results are the first starting torque and the second starting torque respectively. The temperature values in different cases are described later.

[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 driving torque provided by fuel combustion, M fe is the resistance torque of the engine, M ft is the resistance torque of the transmission.

[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; ε is the transmission efficiency from the starting motor to the engine crankshaft end, which is determined by mechanical design and written into the control unit in advance. Generally, it can be taken as 0.97.

[0075] S4.2.1, Power P of the starting motor s is related to the rotational speed n of the starting motor s and P s = f 1 (n s ). This function is determined by the characteristic curve of the starting motor and is written into the control unit in advance; the rotational speed n of the starting motor s = Kn e . K is the ratio of the rotational speed of the starting motor to the rotational speed of the engine, which is determined by mechanical design and written into the control unit in advance.

[0076] S4.3, Calculate the driving torque provided by fuel combustion ρ is the fuel density; m is the fuel injection quantity of the engine; δ is the fuel combustion efficiency.

[0077] S4.3.1, ρ is related to the ambient temperature and fuel type. When T e ≥5°C, for diesel, take 0.82 kg / L, and for gasoline, take 0.75 kg / L; when 5°C > T e ≥ -15°C, for diesel, take 0.83 kg / L, and for gasoline, take 0.76 kg / L; when -15°C > T e , for diesel, take 0.835 kg / L, and for gasoline, take 0.77 kg / L.

[0078] S4.3.2, m is related to the engine speed, and m = f 2 (n e ). This function is determined by the starting fuel injection curve of the engine and is 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. When solving the shortest starting time Minf 7 (t) in the subsequent step S5, since boiler preheating is not carried out, then T′ W = T w , and the corresponding starting torque is the first starting torque; in the subsequent step S7, the corresponding T" w will be solved for boiler heating, then T′ W = T" w . The starting torque calculated therefrom is the second starting torque; γ is the combustion efficiency under standard conditions (ambient temperature is 25 ± 2°C, coolant temperature > 80°C), which is related to the engine speed n e and the fuel injection quantity m. γ = f 3 (n e , m) is determined by experiments or simulations and written into the control unit in advance; T′ air is the air temperature in the intake manifold at the end of preheating. (Used in step S5) or (Used in step S8), T air is the temperature of the intake manifold before preheating; L is the length of the intake pipe; r is the cross-sectional radius of the intake pipe; ρ air is the air density, ρ air = f 4 (T air ), and this function is related to T air and is written into the control unit in advance; t 1 is the first preheating time; t 2 is the second preheating time; P air is the rated power of the intake preheating grille; θ is the heating efficiency of the intake preheating grille, determined by tests or simulations and written into the control unit in advance; β 2 is the second correction coefficient, initially 1.

[0080] S4.4. Calculate the resistance torque M of the engine fe = f 5 (T′ fe , n e ). During the low-temperature starting stage of the engine, the resistance torque is mainly the frictional torque. This function is determined by the engine speed n e and the weighted temperature T′ fe and is written into the control unit according to the results of the reverse drag test during development;

[0081] T′ fe = 0.7T′ w + 0.3T′ O , T′ O is the engine oil temperature at the end of preheating. When the boiler preheating is not carried out, T′ O = T O , and when the boiler preheating is carried out, T′ O = T″ O .

[0082] S4.5. Calculate the resistance torque M of the automatic transmission ft = f 6 (T′ t , n e ). During the low-temperature starting stage of the transmission, the resistance torque is mainly the frictional torque. This function is determined by the engine speed n e and the transmission oil temperature T′ t at the end of preheating and is written into the control unit according to the results of the reverse drag test during development; when the boiler preheating is not carried out, T′ t = T t , and when the boiler preheating is carried out, T′ t = T″ t .

[0083] S5. According to equations ① - ⑤, find the shortest starting time Minf 7 (t);

[0084]

[0085] 0 < t a ≤10………………………………③

[0086] 0 ≤ t 1 ≤45…………………………④

[0087] f 7 (t) = t 1 +t a ………………………………⑤

[0088] Among them, f 7 (t) is the starting time without boiler preheating, P′ s is the power of the starting motor when it just starts to drive the fuel and the fuel has not burned yet. From M s = M fe + M ft , calculate the engine speed n′ e at this time (that is, when the starting motor just starts to drive the fuel and the fuel has not burned yet). Among them, M s , M fe , M ft are calculated by 4.2, 4.4, 4.5 respectively, and then P′ s is calculated by 4.2.1; is the power of the starting motor when the engine speed reaches 400 rpm; it is calculated by 4.2.1; J is the moment of inertia of the engine with the gearbox during the starting stage; M is calculated by 4.1; Q is the maximum available power for the current vehicle start, Q = (SOC - 25%) * C20, C20 is the battery capacity, t 1 is the first preheating time, t a is the theoretical driving time of the engine without boiler preheating; β 3 is the third correction coefficient, initially 1.

[0089] S6. If the formula calculation in step S5 has a positive real - number solution, then according to Minf 7 (t) to determine t 1 and t a ; The control unit outputs an instruction to close the pre - heating grille relay to start intake air pre - heating, the display terminal prompts the start of intake air pre - heating, and at the same time starts timing, until t 1When the starting motor relay is closed, it starts to drive the engine, and the display terminal prompts the start of driving. When the engine speed reaches 400 rpm, the starting motor relay is disconnected. Until the engine speed continues to rise to idle speed, the preheating grille relay is disconnected, and the vehicle starts successfully, ending the starting phase.

[0090] S7. If the formula calculation in step 5 has no positive real solution (indicating that the boiler needs to be preheated), then calculate the cold start for boiler preheating based on the information when the vehicle is in the starting gear, that is, the boiler preheating time is t 3 ; because there is boiler heating, at the end of preheating in 4.3.3, 4.4, and 4.5, the engine coolant temperature T′ w , the engine oil temperature T′ O and the transmission oil temperature T′ t are not equal to the temperature when the key is in the starting gear. The function f 8 is the sum of the engine resistance torque and the transmission resistance torque when the engine speed is 400 rpm, that is, f 8 = f s - f 5 (T′ fe , 400) + f 6 (T′ t , 400). Calculate f 8 when it is the smallest, and theoretically, the engine coolant temperature T″ w , the engine oil temperature T″ O and the transmission oil temperature T″ t are as follows:

[0091] 0.0012(T″ w - T w ) + 0.0005(T″ o - T o ) + 0.0005(T″ t - T t ) = t 3 P f αβ 4 ⑥

[0092]

[0093] T w < T″ w …………………………⑧

[0094] T t < T″ t …………………………⑨

[0095] P fP is the power generated by boiler combustion; α is the thermal efficiency of the liquid heating system during boiler combustion, which is determined according to system tests and written into the control unit in advance; N is the heat ratio obtained by the engine coolant system and the engine oil, which is determined according to system tests and written into the control unit in advance; β 4 is the fourth correction factor, with an initial value of 1.

[0096] S8. According to the formula, calculate the shortest start-up time Minf 9 (t);

[0097]

[0098] where P b is the electric power of the boiler during operation; M 2 is calculated from 4.1, where T′ w , T′ O and T′ t and T″ w , T″ O and T″ t obtained from S7.

[0099] It should be noted that the t 1 , t 2 and t 3 corresponding preheating times in steps S5 and S8 are not the actual preheating times of the corresponding devices, but the action times of other devices after the corresponding devices preheat for the corresponding time, that is, t 1 , t 2 is the time from when the preheating grille starts to intake air for preheating to when the starting motor relay closes. After the time, the preheating grille will continue to preheat until the preheating grille relay disconnects; t 3 is the time from when the boiler starts preheating to when the preheating grille starts to intake air for preheating. After the time, the boiler will continue to preheat until the boiler relay disconnects.

[0100] S9. If the formula calculation in step S8 has a positive real solution, then according to Minf 9 (t), determine the t b , t 2 and t 3 , t 2 is the second preheating time, t b is the theoretical driving time of the engine during boiler preheating (i.e., the theoretical time from when the starting motor relay closes to when it disconnects); t 3 is the third preheating time; the control unit outputs an instruction to close the boiler relay, the boiler starts to work, the display terminal prompts the start of boiler preheating, and at the same time, adjust the opening of the proportional valve of the liquid heating pipeline to heat the engine and the transmission. The opening of the proportional valve is based on the engine coolant temperature T″′ Wand the transmission oil temperature T″′ t is dynamically adjusted. The opening degree B of the proportional valve is 50+(T″′ w -T″′ t ). B ranges from 10 to 90. That is, if the calculated value exceeds the upper limit of 90, it is directly set to 90; if the calculated value is lower than the lower limit of 10, it is directly set to 10. Part of the heat from the boiler heating is used to heat the engine and the other part is used to heat the transmission. The opening degree of the proportional valve corresponds to the part of the heat supplied by the boiler heating to the engine. That is, when B is set to 80, it means that 80% of the heat from the boiler heating is used to heat the engine and 20% of the heat is used to heat the transmission. When the boiler relay closes, the timing starts. At t 3 , the control unit outputs an instruction to close the preheating grille relay to start intake air preheating, and the display terminal prompts the start of intake air preheating. At the same time, the timing starts. At t 2 , the starting motor relay is closed to start dragging the engine, and the display terminal prompts the start of dragging. When the engine speed reaches 400 rpm, the starting motor relay is disconnected. After the engine speed continues to rise to idle speed, the preheating grille relay and the boiler relay are disconnected, and the vehicle starts successfully, and the starting stage ends.

[0101] S10. If the formula calculation in step S8 has no positive real solution, the control unit outputs an instruction to close the boiler relay according to the calibrated preheating time (including the calibrated fourth preheating time and fifth preheating time), and the boiler starts to work. The display terminal prompts the start of boiler preheating. At the same time, the opening degree of the proportional valve in the liquid heating pipeline is adjusted. The opening degree of the proportional valve is dynamically adjusted according to the real-time detected engine coolant temperature T″′ w and the transmission oil temperature T″′ t . The opening degree B of the proportional valve is 50(T″′ w -T″′ t ). B ranges from 10 to 90, and the unit is %. That is, if the calculated value exceeds the upper limit of 90, it is directly set to 90; if the calculated value is lower than the lower limit of 10, it is directly set to 10. When the boiler relay closes, the timing starts. At the fifth preheating time (such as 1500 s), the control unit outputs an instruction to close the preheating grille relay to start intake air preheating, and the display terminal prompts the start of intake air preheating. At the same time, the timing starts. At the fourth preheating time (such as 45 s), the starting motor relay is closed to start dragging the engine, and the display terminal prompts the start of dragging. When the engine speed reaches the set speed (400 rpm), the starting motor relay is disconnected. When the engine speed reaches idle speed, the preheating grille relay and the boiler relay are disconnected, and the vehicle starts successfully, and the starting stage ends.

[0102] S11. In the above steps S6, S9, and S10, if the engine is continuously dragged and the engine speed never reaches the set speed, but the dragging time reaches the set time, the starting motor relay is disconnected to stop dragging the engine;

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

[0104] After stopping dragging the engine, in a few cases, the engine will continue to run. If the engine continues to run until the speed reaches the set speed, then after the engine speed continues to rise to the idle speed, the preheating grille relay and the boiler relay are disconnected, and the vehicle starts successfully at low temperature.

[0105] It should be noted that when dragging the engine, under normal circumstances, the engine speed may 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 there are other equipment failures, the engine will be dragged until the engine speed still cannot reach the set speed at the set time, and then the dragging stops. 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 times.

[0106] S12. In each cycle, if the vehicle starts successfully in the above steps S6, S9, and S10, or the number of consecutive failures of the vehicle to start at low temperature in step S11 reaches the set number, it is necessary to determine whether to modify the corresponding correction coefficient (i.e., the above β 1 、β 2 、β 3 、β 4 ) according to the corresponding parameters. Specifically, based on the actual parameters of the engine or the battery parameters, the correction coefficient after the vehicle starts this time is determined. The correction coefficient after the vehicle starts is compared with the correction coefficient before the vehicle starts, and whether to modify the correction coefficient is determined according to the comparison result. The correction coefficients before the vehicle starts are all known values, which are calibration values or values determined (modified) after the previous start.

[0107] The specific determination process of the correction coefficient after the vehicle starts is as follows: Based on the actual temperature of the engine intake manifold after the vehicle starts, through the formula in the above 4.3.3 (i.e., replacing T′ in the formula with the actual temperature air ) the β 2 after the vehicle starts can be calculated. Based on the actual dragging time of the engine (i.e., the actual time from the closing to the disconnection of the starting motor relay), through the above formula ② or (i.e., replacing t in the formula with the actual dragging time a or t b ) the β 3 after the engine starts can be calculated.. Based on the actually detected engine coolant temperature T″′ after the vehicle starts w , the engine oil temperature T″′ O and the transmission oil temperature T″′ t Through the above formula ⑥ (i.e., replacing T″ in the formula with the actually detected value w , T″ O and T″ t ), the β after the vehicle starts can be calculated 4 . For β 1 is determined according to the battery power. If the battery is fully charged after the vehicle starts this time, then β after the vehicle starts is calculated by reverse deduction according to the process of calculating SOC in S1 1 , at this time SOC is 100%, that is, by to determine SOC′, and then determine β through SOC′ 1 ; if the battery is not fully charged after the vehicle starts this time, then it is determined that β after the vehicle starts 1 is equal to β before the vehicle starts 1 .

[0108] The process of determining whether to modify the correction coefficient according to the comparison result is as follows: Calculate the difference β between the correction coefficient after the vehicle starts and the correction coefficient before the vehicle starts x , that is, the differences corresponding to β x are respectively recorded as (x = 1, 2, 3 or 4 corresponds to β 1 , β 2 , β 3 , β 4 ), if the absolute value of the difference of a certain correction coefficient for three consecutive times is greater than the set threshold (i.e., three consecutive times ) and the absolute value of the average value of the differences for three consecutive times is greater than the set threshold (i.e., ), then it is determined that the corresponding correction coefficient needs to be modified, and the average value of the differences for three consecutive times is used to replace the correction coefficient before the current engine starts for parameter calculation during the next low-temperature start of the vehicle.

[0109] It should be understood that the specific order or hierarchy of the steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of the steps in the process can be rearranged without departing from the protection scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0110] To make the description of the present disclosure more detailed and complete, the above provides an illustrative description of the embodiments and specific examples of the present invention; however, this is not the only form for implementing or applying the specific examples of the present invention. The embodiments cover the features of multiple specific examples and the method steps and their sequences for constructing and operating these specific examples. However, other specific examples can also be used to achieve the same or equivalent functions and step sequences.

[0111] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be construed as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly recited in each claim. On the contrary, as reflected by the appended claims, the present invention lies in a state with fewer features than all the features of the disclosed single embodiment. Therefore, the appended claims are hereby clearly incorporated into the detailed description, where each claim stands alone as a separate preferred embodiment of the present invention.

[0112] In the above detailed description, various features are combined in a single embodiment to simplify the present disclosure. This method of disclosure should not be construed as reflecting an intention that the embodiments of the claimed subject matter require more features than are clearly recited in each claim. On the contrary, as reflected by the appended claims, the present invention lies in a state with fewer features than all the features of the disclosed single embodiment. Therefore, the appended claims are hereby clearly incorporated into the detailed description, where each claim stands alone as a separate preferred embodiment of the present invention.

[0113] The above are only the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The content not described in detail in this specification belongs to the well-known prior art of those skilled in the art.

Claims

1. A vehicle low temperature starting method based on electric energy distribution, characterized in that: When the vehicle reaches the starting gear, the current real-time battery power percentage is determined and the starting temperature is judged. If the starting temperature is lower than the temperature threshold, whether to start the vehicle is determined based on the real-time battery power percentage; If it is determined to start the vehicle, a first starting torque without boiler preheating is calculated, and a first preheating time for preheating the grid before the engine is started is determined based on the first starting torque; or calculating a second starting torque for preheating the boiler, determining a second preheating time of the preheating grid before the engine starts and a third preheating time of the boiler based on the second starting torque, or determining a fourth preheating time of the preheating grid before the engine starts and a fifth preheating time of the boiler based on the second starting torque; Controlling the first preheating time of air intake preheating of the preheating grid, or controlling the second preheating time of air intake preheating of the preheating grid and the third preheating time of boiler preheating, or controlling the fourth preheating time of air intake preheating of the preheating grid and the fifth preheating time of boiler preheating; After the preheating time is reached, the starter motor relay is closed to start the engine. After the engine speed reaches idle speed, the vehicle starts successfully at low temperature.

2. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: The starting temperature is determined by the following formula: Where, 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, initial engine coolant temperature, initial engine oil temperature, and initial transmission oil temperature, respectively, and A1+A2+A3+A4=1.

3. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: The process of determining the real-time battery power percentage is as follows: 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 factor and the first correction factor; Calculate the real-time battery power percentage based on the instantaneous battery power percentage using the formula. Among them, SOC is the real-time battery power percentage; SOC′ is the instantaneous battery power percentage; V is the real-time battery voltage; I is the real-time total battery current; t is the time period from the moment the vehicle is powered on to the moment the vehicle reaches the starting gear.

4. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: The step of determining whether to start the vehicle according to the real-time battery power percentage includes: If the real-time battery power percentage is less than the first SOC setting value, the vehicle will not be started; If the real-time battery power percentage is greater than or equal to the first SOC setting value and less than the second SOC setting value, a low battery alarm is issued, and a pop-up window prompts the driver to choose whether to start the vehicle; If the real-time battery power percentage is greater than or equal to the second SOC setting value, it is directly determined to start the vehicle.

5. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: The first starting torque or the second starting torque is determined by the following formula: M=M s +M e -M fe -M ft Where, M is the starting torque; M s Torque provided to the starting motor; M e The power torque provided for fuel combustion; M fe is the resistance torque of the engine; M ft is the resistance torque of the gearbox.

6. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: The method of determining a first preheating time of the preheating grid before engine start based on the first starting torque; or determining a second preheating time of the preheating grid before engine start and a third preheating time of the boiler based on the second starting torque, or determining a fourth preheating time of the preheating grid before engine start and a fifth preheating time of the boiler based on the second starting torque, comprises: Based on a first formula including a first starting torque, a shortest starting time without boiler preheating is calculated, and if the calculation result has a positive real number solution, a first preheating time of a preheating grid before the engine is started is determined based on the positive real number solution; if the calculation result has no positive real number solution, the shortest starting time with boiler preheating is calculated based on a second formula including a second starting torque; If the calculation result has a positive real number solution, the second preheating time of the preheating grille before the engine is started and the third preheating time of the boiler are determined based on the positive real number solution; if the calculation result has no positive real number solution, the fourth preheating time of the preheating grille before the engine is started and the fifth preheating time of the boiler are determined based on the calibrated preheating time.

7. The vehicle low temperature starting method based on electric energy distribution according to claim 6, characterized in that: The first formula is: 0<t a ≤10 0≤t1≤45 f7(t)=t1+t a Wherein, f7(t) is the start-up time without boiler preheating; t1 is the first preheating time; t a P is the theoretical drag time of the engine without boiler preheating; air is the rated power of the preheating grid; P′ s It is the power of the starter motor when it just starts to run and the fuel has not yet burned; is the starting motor power when the engine speed reaches 400rpm; Q is the maximum power that is expected to be available for the current vehicle start; J is the rotational inertia of the engine with the gearbox during the starting phase; M1 is the first starting torque; n e is the engine speed; β3 is the third correction coefficient.

8. The vehicle low temperature starting method based on electric energy distribution according to claim 6, characterized in that: The second formula is: 0<t3≤1500 0<t b ≤10 0<t2≤45 f9(t))=t2+t b +t3 Wherein, f7(t) is the start time for boiler preheating; t2 is the second preheating time; t3 is the third preheating time; t b P is the theoretical drag time of the engine during boiler preheating; b P is the electric power of the boiler when it is working; air is the rated power of the preheating grid; P′ s It is the power of the starter motor when it just starts to run and the fuel has not yet burned; is the starting motor power when the engine speed reaches 400rpm; Q is the maximum power that is expected to be available for the current vehicle start; J is the rotational inertia of the engine with the gearbox during the starting phase; M2 is the second starting torque; n e is the engine speed; β3 is the third correction coefficient.

9. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: After determining the first preheating time of the preheating grille before starting the engine, close the preheating grille relay, and the preheating grille begins to preheat the intake air. After the preheating grille is preheated for the first preheating time, close the starter motor relay to start dragging the engine. After the engine speed reaches the set speed, disconnect the starter motor relay. After the engine speed reaches idle speed, disconnect the preheating grille relay, and the vehicle starts successfully at low temperature.

10. The vehicle low temperature starting method based on electric energy distribution according to claim 1, characterized in that: After determining the second preheating time of the preheating grille and the third preheating time of the boiler before starting the engine, first close the boiler relay and the boiler starts preheating. At the same time, adjust the opening of the proportional valve of the liquid heating pipeline to heat the engine and gearbox. After the boiler is preheated for the third preheating time, close the preheating grille relay and the preheating grille starts intake air preheating. After the preheating grille is preheated for the second preheating time, close the starter motor relay to start dragging the engine. After the engine speed reaches the set speed, disconnect the starter motor relay. After the engine speed reaches idle speed, disconnect the preheating grille relay and boiler relay. The vehicle starts successfully at low temperature.

11. The vehicle low temperature starting method based on electric energy distribution according to claim 9 or 10, characterized in that: If the engine speed does not reach the set speed after the engine is continuously dragged for the set time, the starter motor relay is disconnected to stop dragging the engine; After stopping the engine from dragging, if the engine stops running, it is determined that the vehicle has failed to start at low temperature, and the number of consecutive failures of the vehicle to start at low temperature is recorded. If the number of consecutive failures of the vehicle to start at low temperature reaches the set number, the vehicle will not be started; otherwise, the actual SOC value of the battery is returned to determine; 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 after the engine speed reaches the idle speed, and the vehicle is successfully started at low temperature.

12. The vehicle low temperature starting method based on electric energy distribution according to claim 11, characterized in that: After the vehicle starts successfully at low temperature or the number of consecutive failures in starting at low temperature reaches a set number, a correction coefficient after the vehicle starts is determined based on actual parameters of the engine, and the correction coefficient after the vehicle starts is compared with the correction coefficient before the vehicle starts to determine whether the correction coefficient needs to be modified.

13. The vehicle low temperature starting method based on electric energy distribution according to claim 12, characterized in that: 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 for three consecutive times is greater than the set threshold and the absolute value of the average value of the difference for three consecutive times is greater than the set threshold, it is determined that the correction coefficient needs to be modified, and the correction coefficient before the current vehicle is started is replaced by the average value of the difference for three consecutive times for parameter calculation during the next low-temperature start of the vehicle.

Images