A method for controlling engine target coolant temperature
By dynamically optimizing the target water temperature control method and the self-learning correction coefficient, the problem of low closed-loop control accuracy when the engine target water temperature changes greatly is solved, achieving precise water temperature control and improved robustness, and adapting to parameter adjustments throughout the engine's life cycle.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DONGFENG MOTOR GRP
- Filing Date
- 2023-09-13
- Publication Date
- 2026-05-26
AI Technical Summary
When the target engine coolant temperature changes significantly, the closed-loop control has low accuracy and poor robustness, and the fan speed is not steplessly controllable, resulting in insufficient coolant temperature control accuracy.
By dynamically optimizing the target water temperature control method, combining atmospheric temperature, actual water temperature and preset value, the fan speed is adjusted to achieve precise control. A self-learning correction coefficient is used to update the fan speed to adapt to engine aging and optimize the engine target water temperature.
It improves the accuracy and robustness of engine target coolant temperature control, avoids the problem of frequent or untimely fan activation, and adapts to parameter self-tuning throughout the engine's life cycle.
Smart Images
Figure CN117231343B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of engine control technology, specifically relating to a method for controlling engine target coolant temperature. Background Technology
[0002] An engine is a power source that converts chemical energy into mechanical energy through combustion, which generates a large amount of heat energy in the process. From the perspectives of power, economy and emissions performance, engines are best operated at their optimal temperature, so they need to be equipped with a suitable cooling system.
[0003] Setting the target coolant temperature for the engine is crucial for engine power, fuel economy, and engine lifespan. However, significant variations in the target coolant temperature can lead to issues such as low closed-loop control accuracy and poor robustness. Therefore, a target coolant temperature control method for the engine is proposed. Summary of the Invention
[0004] The purpose of this invention is to provide a method for controlling the target coolant temperature of an engine, which solves the problems of low closed-loop control accuracy and poor robustness when the target coolant temperature of the engine changes significantly, since the fan speed is not infinitely controllable.
[0005] The technical solution adopted in this invention is as follows:
[0006] A method for controlling a target coolant temperature in an engine includes the following steps:
[0007] Determine if the original target water temperature maintenance conditions are met; if yes, maintain the original target water temperature; otherwise, proceed to dynamic optimization of the target water temperature.
[0008] When the atmospheric temperature is lower than the first preset temperature;
[0009] If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the first low temperature threshold.
[0010] If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
[0011] When the atmospheric temperature is higher than the second preset temperature; wherein the second preset temperature is higher than the first preset temperature;
[0012] If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the second low temperature threshold; wherein, the second low temperature threshold is less than the first low temperature threshold.
[0013] If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
[0014] When the atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature;
[0015] If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
[0016] If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
[0017] Furthermore, the conditions for maintaining the original target water temperature are: the cooling fan is not turned on or the cooling fan has been turned off for more than a preset time, or the actual water temperature in this driving cycle does not exceed the original target water temperature, or the absolute value of the difference between the original target water temperature and the actual water temperature does not exceed the preset temperature value.
[0018] Furthermore, the preset time is 5 seconds.
[0019] Furthermore, when the atmospheric temperature is lower than the first preset temperature;
[0020] If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the first low temperature threshold.
[0021] T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k), (T CoolantInt -T CoolantAct -C1+D1)]
[0022] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value:
[0023] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0024] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct The actual water temperature is given by f(T), where C1 is the preset temperature value and D1 is the first low temperature threshold.CoolantInt ,k) is the target water temperature correction value, T CoolantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
[0025] Furthermore, when the atmospheric temperature is higher than the second preset temperature; wherein the second preset temperature is higher than the first preset temperature;
[0026] If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the second low-temperature threshold; wherein, the second low-temperature threshold is less than the first low-temperature threshold.
[0027] T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k), (T CoolantInt -T CoolantAct -C1-D2)]
[0028] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value:
[0029] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0030] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct The actual water temperature is given by f(T), where C1 is the preset temperature value and D2 is the second low temperature threshold. CoolantInt ,k) is the target water temperature correction value, T C oo lantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
[0031] Furthermore, when the atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature;
[0032] If the original target water temperature is higher than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
[0033] T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k), (T CoolantInt -TCoolantAct -C1)]
[0034] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value:
[0035] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0036] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct C1 is the actual water temperature, and f(T) is the preset temperature value. CoolantInt ,k) is the target water temperature correction value, T C oo lantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
[0037] Furthermore, the formula for calculating the adjustment characteristic value of the target water temperature is as follows:
[0038]
[0039] In the formula, n is the engine speed, and r Octane f(n,r) is the octane number coefficient of petroleum products. Octane (by n and r) Octane Calibration obtained; phi Knock For the current detonation delay ignition angle, phi KnockMax The maximum ignition angle delayed by detonation, dp MapAct The actual rate of change of gas pressure entering the cylinder. Depend on and dp MapAct Calibration obtained; dM SprkReq To request the rate of change of torque in the fire circuit, T CoolantErr The original target water temperature T CoolantInt Compared with the actual water temperature T CoolantAct The difference, f(dM) SprkReq ,T CoolantErr ) by dM SprkReq and T CoolantErr Calibration obtained; r Adp This is the self-learning correction coefficient.
[0040] Furthermore, self-learning correction coefficient update methods include:
[0041] If the difference between the target water temperature and the actual water temperature after dynamic optimization exceeds the preset temperature range for more than the first preset time T1 for more than X times in the current driving cycle, and knocking occurs in each of these X occurrences, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and it increases at the first rate K1; and the counter is reset to zero, and it is incremented again in the current driving cycle after the self-learning correction coefficient update learning conditions are met.
[0042] If the above conditions are not met, and the number of times the difference between the target water temperature after dynamic optimization and the actual water temperature exceeds the preset temperature value C1 for more than the first preset time T1 in the current driving cycle exceeds the preset number N1, and knocking occurs in each of the occurrences within the number X, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and it increases at the second rate; and the counter is reset to zero, and it is accumulated again in the current driving cycle after the self-learning correction coefficient update learning conditions are met.
[0043] If the above conditions are not met, and the number of times the difference between the target water temperature after dynamic optimization and the actual water temperature exceeds the preset temperature value C1 for more than the first preset time T1 in the current driving cycle exceeds the preset number N1, and knocking does not occur in every occurrence within the number of occurrences X, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and the target water temperature self-learning correction coefficient will not be updated for the time being; and the counter is reset to zero, and will be accumulated again in the current driving cycle after the self-learning correction coefficient update learning conditions are met.
[0044] If the above conditions are not met, and the difference between the target water temperature after dynamic optimization in the current driving cycle and the actual water temperature does not exceed the preset temperature value C1, then the target water temperature self-learning correction coefficient update state is the downward learning state, and the target water temperature self-learning correction coefficient will not be updated for the time being.
[0045] If none of the above conditions are met, determine the update status of the target water temperature self-learning correction coefficient in the previous sampling period; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in an upward learning state, then the target water temperature self-learning correction coefficient increases at the third rate K3; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in a downward learning state, then the target water temperature self-learning correction coefficient decreases at the fourth rate K4; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in a no-update state, then it remains unchanged; at the same time, in the current sampling period, the update status of the target water temperature self-learning correction coefficient is set to a no-update state.
[0046] The priority of the above 5 cases decreases from one to the next, and only one case is executed in each sampling period.
[0047] Furthermore, the self-learning correction coefficient update learning condition is as follows:
[0048] The fan should be turned on or off within a preset time.
[0049] The vehicle mileage since the last learning correction coefficient update exceeds the preset mileage value;
[0050] The atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature;
[0051] If all three conditions above are met simultaneously, then the self-learning correction coefficient update learning condition is satisfied.
[0052] Furthermore, the first preset temperature is -15℃, the second preset temperature is 45℃, the preset temperature value is 2℃, the first low temperature threshold is 0.8℃, the second low temperature threshold is 0.5℃, the preset mileage value is 20,000 kilometers, the preset temperature range is -5℃ to 5℃, the first preset time T1 is 0.5s, the preset number of times N1 is 5 times, the first rate K1 is 0.03 / 10ms, the second rate is 0.01 / 10ms, the third rate is 0.005 / 10ms, and the fourth rate is -0.003 / 10ms.
[0053] Compared with the prior art, the present invention has the following advantages and beneficial effects:
[0054] This invention improves the target water temperature control method under conditions of fan on or knocking, or suppresses knocking, while also balancing the achievement of engine torque; it also avoids control parameter deviations caused by aging engine components, and is applicable to parameter self-tuning after the engine's life cycle has progressed. Attached Figure Description
[0055] Figure 1 This is a flowchart of the engine target water temperature control method according to an embodiment of the present invention. Detailed Implementation
[0056] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.
[0057] A typical engine cooling system includes an engine outlet temperature sensor, an atmospheric temperature sensor (or atmospheric temperature signal), a vehicle speed sensor (or vehicle speed signal), a water pump, a thermostat (thermal management module), and a cooling fan.
[0058] Engine outlet temperature sensor is used to detect the temperature of the coolant at the engine outlet.
[0059] An atmospheric temperature sensor or atmospheric temperature signal is used; the engine cooling system is hardwired to the atmospheric temperature sensor or receives the atmospheric temperature signal via a network such as CAN.
[0060] The vehicle speed sensor or vehicle speed signal is either hard-wired to the engine cooling system or received via a network such as CAN.
[0061] Water pumps control the circulation of cooling water;
[0062] The thermostat (or thermal management module) is open, indicating that some coolant is returned to the engine inlet after being cooled by the radiator.
[0063] The cooling fan has only two stages, meaning two speeds: low and high, with fixed power, used to cool the cooling water flowing through the radiator.
[0064] Since the fan speed is not infinitely controllable and the target water temperature changes significantly, the water temperature control cannot be precise. Therefore, software optimization is used to improve the water temperature control accuracy and avoid the problem of fluctuating water temperature caused by frequent or untimely fan operation.
[0065] The engine target coolant temperature control method of the present invention, such as Figure 1 As shown, it includes:
[0066] 1. When the cooling fan is not turned on, or when the cooling fan has been off for more than a preset time T0 (T0 is 5s in this example), or when the actual water temperature in this driving cycle does not exceed the target water temperature, or when the absolute value of the difference between the original target water temperature and the actual water temperature does not exceed the preset value C1, C1 is 2℃ in this example. The target water temperature is not optimized and the original target water temperature is maintained. That is, at this time T CoolantDsrd =T CoolantInt , among which, T CoolantDsrd To optimize the target water temperature after treatment, T CoolantInt The original target water temperature.
[0067] II. If the first condition is not met, then proceed to dynamic optimization of the target water temperature:
[0068] 1) When the atmospheric temperature is lower than the preset temperature T1, this example uses -15℃;
[0069] If the original target water temperature T CoolantInt Greater than the actual water temperature T CoolantAct hour:
[0070] T CoolantDsrd =T CoolantInt-min[f(T CoolantInt ,k), (T CoolantInt -T CoolantAct -C1+D1)]
[0071] If the original target water temperature T CoolantInt No greater than the actual water temperature T CoolantAct hour:
[0072] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0073] Where D1 is the low temperature threshold, and D1 is less than C1. In this example, it is taken as 0.8℃. When the ambient temperature is low and the original target water temperature is high, the engine heat dissipation capacity is strong. Since it is necessary to provide heating in the passenger cabin, the engine water temperature control should not be too precise to ensure that the temperature in the passenger cabin is relatively stable.
[0074] 2) When the ambient temperature is higher than the preset temperature T2, this example uses 45℃;
[0075] If the original target water temperature T CoolantInt Greater than the actual water temperature T CoolantAct hour:
[0076] T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k), (T CoolantInt -T CoolantAct -C1-D2)]
[0077] If the original target water temperature T CoolantInt No greater than the actual water temperature T CoolantAct hour:
[0078] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0079] Wherein, D2 is the low temperature threshold, and D2 is less than C1. In this example, it is taken as 0.5℃. When the ambient temperature is high and the original target water temperature is high, the engine heat dissipation capacity is poor. Since it is necessary to provide cold air to the passenger cabin, the air conditioning control capacity is strong, and the engine heat generation capacity is strong. It is necessary to further reduce the target water temperature to ensure the comfort of the passenger cabin.
[0080] 3) When the atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2;
[0081] If the original target water temperature T CoolantInt Greater than the actual water temperature T CoolantAct hour:
[0082] T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k), (T CoolantInt -T CoolantAct -C1)]
[0083] If the original target water temperature T CoolantInt No greater than the actual water temperature T CoolantAct hour:
[0084] T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k), (T CoolantAct -T CoolantInt -C1)]
[0085] Where k is the adjustment characteristic value of the target water temperature. When the atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2, in order to avoid water temperature fluctuations exceeding C1 after the fan is turned on or the fan is turned off within T0, it is designed to (i.e., the difference between the optimized target water temperature and the actual water temperature is controlled within ±2℃; at the same time, when the original target water temperature remains unchanged, the actual water temperature change is controlled within ±2℃). The values in this example are as follows. After determining the adjustment characteristic value k of the target water temperature when the atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2, D1 and D2 are then determined for other atmospheric temperatures. The method of determination is based on the subjective feeling of the passengers in the cabin, and the difference between the optimized target water temperature and the actual water temperature is controlled within ±3℃. At the same time, when the original target water temperature remains unchanged, the actual water temperature change is controlled within ±3℃.
[0086] The larger the target water temperature adjustment characteristic value k, the greater the target water temperature correction. CoolantInt The calibration of k is shown in Table 1.
[0087] Table 1 f(T) CoolantInt ,k) Calibration Table
[0088]
[0089] The adjustment characteristic value k of the target water temperature is calculated as follows:
[0090]
[0091] Where n is the engine speed, r Octane This refers to the octane rating coefficient of the oil product (compared to the octane rating r mentioned in patent CN202010608134.7 "A Method and System for Self-Learning Octane Number of Oil Products"). OctaneRatio (with the same physical meaning), phi Knock For the current detonation delay ignition angle, phi KnockMax The maximum ignition angle delayed by detonation (10° in this example), dp MapAct The actual rate of change of gas pressure entering the cylinder, dM SprkReq To request the rate of change of torque in the fire circuit, T CoolantErr The original target water temperature T CoolantInt Compared with the actual water temperature T CoolantAct The difference, r Adp To learn the correction coefficient.
[0092] The reason for using the above specific parameters as adjustment characteristic values for the target coolant temperature is primarily because: when the octane rating of the fuel increases the likelihood of knocking, the target coolant temperature needs to be adjusted appropriately to avoid the risk of increased knocking due to excessively high temperature control requirements; when the knocking angle is severe, the target coolant temperature needs to be adjusted appropriately to avoid the risk of increased knocking due to excessively high temperature control requirements; and when a large torque is requested, the original target coolant temperature needs to be maintained as much as possible to improve engine combustion efficiency and achieve the required torque. Furthermore, due to the aging of engine components, the adjustment characteristic values may shift, necessitating self-learning updates.
[0093] First, determine the parameters f(n,r) Octane This parameter is designed to adjust the target water temperature appropriately when the octane number of the oil increases the likelihood of knocking, thus avoiding the risk of increased knocking due to excessively high water temperature control requirements. The calibration method for this parameter is as follows: when the ambient temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2, for oils with different octane numbers, the water temperature fluctuation exceeds C1 within T0 after the fan is turned on or after the fan is turned off (i.e., the difference between the optimized target water temperature and the actual water temperature is controlled within ±2℃; simultaneously, when the original target water temperature remains unchanged, the actual water temperature change is controlled within ±2℃). Based on this, the specific calibration parameters for this example are shown in Table 2.
[0094] Table 2 f(n,r) Octane Calibration table
[0095]
[0096] Secondly, determine the parameters. As shown in Table 3, this parameter is designed to adjust the target water temperature appropriately when the knocking angle is severe, so as to avoid the risk of increased knocking due to excessively high water temperature control requirements. The calibration method of this parameter is as follows: when the atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2, under different guaranteed knocking angles and different intake pressure change rates (the greater the intake pressure change rate, the greater the risk of knocking), the water temperature fluctuation exceeds C1 after the fan is turned on or within T0 when the fan is turned off. This is designed to keep the difference between the target water temperature and the actual water temperature within ±2℃ after optimization; at the same time, when the original target water temperature remains unchanged, the actual water temperature change is controlled within ±2℃.
[0097] Table 3 Calibration table
[0098]
[0099]
[0100] Next, determine the parameter f(dM) SprkReq ,T CoolantErr As shown in Table 4, this parameter is designed to improve engine combustion efficiency when a large requested arc torque is required. It is necessary to maintain the original target water temperature as much as possible to achieve the required torque. The calibration method for this parameter is as follows: when the atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2, under different water temperature differences and different rates of change of requested arc torque, the engine torque control accuracy is within the required range (in this example, the control accuracy requirement is that the difference between the requested arc torque and the actual arc torque does not exceed ±5Nm), and the water temperature fluctuation exceeds C1 after the fan is turned on or the fan is turned off within T0 (that is, the difference between the target water temperature and the actual water temperature after optimization is controlled within ±2℃; at the same time, when the original target water temperature remains unchanged, the actual water temperature change is controlled within ±2℃).
[0101] Table 4 f(dM) SprkReq ,T CoolantErr Calibration table
[0102]
[0103] Finally, (1+r) was determined. Adp The target water temperature self-learning correction factor r in ) Adp When the vehicle rolls off the production line, the target water temperature self-learning correction factor r Adp The value is 0, and it continuously learns itself throughout the engine's life cycle. This learned value is stored in the controller's EEPROM after power-off.
[0104] The conditions for self-learning are:
[0105] 1. The time between fan startup and fan shutdown shall not exceed T0.
[0106] 2. The vehicle mileage since the last target water temperature self-learning correction factor update exceeds the preset value, which is 20,000 kilometers in this example.
[0107] 3. The atmospheric temperature is not lower than the preset temperature T1 and not higher than the preset temperature T2.
[0108] If all three conditions are met, then the self-learning condition is satisfied. The self-learning method is as follows:
[0109] 1. If the target water temperature T after optimization in the current driving cycle CoolantDsrd Compared with the actual water temperature T CoolantAct If the difference between C2 and C2 (±5℃ in this example) exceeds the preset time T1 (0.5s in this example) for more than X times (counted by a counter) and exceeds the preset number N1 (5 in this example), and a knocking event occurs in every occurrence within the X times, then the target water temperature self-learning correction factor update state is in the upward learning state, and r... Adp The counter increases at a certain rate of K1 = 0.03 / 10ms. The counter is then reset to zero, and it increments again within the current driving cycle after the condition is met.
[0110] 2. If the above conditions are not met, and the target water temperature T after optimization in the current driving cycle is... CoolantDsrd Compared with the actual water temperature T CoolantAct If the number of times X occurs where the difference between C1 and C1 exceeds a preset time T1, and a knocking event occurs in each of these occurrences within the specified number X, then the target water temperature self-learning correction factor update state is in an upward learning state, and r... Adp The counter increases at a certain rate of K2 = 0.01 / 10ms. The counter is then reset to zero, and it increments again within the current driving cycle after the condition is met.
[0111] 3. If the above conditions are not met, and the target water temperature T after optimization in the current driving cycle is... CoolantDsrd Compared with the actual water temperature T CoolantAct If the number of times X occurs when the difference between C1 and C1 exceeds the preset time T1, and not every occurrence within the number X results in a knocking event, then the target water temperature self-learning correction factor update state is in an upward learning state, and r is not updated at this time. Adp The counter is reset to zero, and then incremented again within the current driving cycle once the conditions are met.
[0112] 4. If the above conditions are not met, and the target water temperature T after optimization in the current driving cycle is... CoolantDsrd Compared with the actual water temperature T CoolantActIf the difference does not exceed C1, the target water temperature self-learning correction factor update state is in the downward learning state, and r is not updated at this time. Adp .
[0113] 5. If none of the above conditions are met, determine the update status of the target water temperature self-learning correction factor in the previous sampling period. If the update status of the target water temperature self-learning correction factor in the previous sampling period is in the upward learning state, then r Adp The rate K3 increases at a certain rate of 0.005 / 10ms; if the target water temperature self-learning correction factor update state in the previous sampling period is in a downward learning state, then r Adp The rate decreases at a certain rate, K4 = -0.003 / 10ms. If the target water temperature self-learning correction factor update state in the previous sampling period was not updated, then r Adp The status remains unchanged. Meanwhile, the target water temperature self-learning correction factor update state is set to "no update" during this cycle.
[0114] The priority of the above five cases decreases from one to the next. Furthermore, only one case is executed during each sampling period (10ms in this example).
[0115] The above completes the description of the method for controlling the engine target coolant temperature.
[0116] It should be noted that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0117] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this invention.
[0118] Those skilled in the art will readily understand that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for controlling the target coolant temperature of an engine, characterized in that, Includes the following steps: Determine if the original target water temperature maintenance conditions are met; if yes, maintain the original target water temperature; otherwise, proceed to dynamic optimization of the target water temperature. When the atmospheric temperature is lower than the first preset temperature; If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the first low temperature threshold. If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value. When the atmospheric temperature is higher than the second preset temperature; wherein the second preset temperature is higher than the first preset temperature; If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the second low temperature threshold; wherein, the second low temperature threshold is less than the first low temperature threshold. If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value. When the atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature; If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value. If the original target water temperature is not greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value.
2. The engine target water temperature control method according to claim 1, characterized in that, The conditions for maintaining the original target water temperature are: the cooling fan is not turned on or the cooling fan has been turned off for more than a preset time, or the actual water temperature in this driving cycle does not exceed the original target water temperature, or the absolute value of the difference between the original target water temperature and the actual water temperature does not exceed the preset temperature value.
3. The engine target water temperature control method according to claim 2, characterized in that, The preset time is 5 seconds.
4. The engine target water temperature control method according to claim 1, characterized in that, When the atmospheric temperature is lower than the first preset temperature; If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the first low temperature threshold. T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k),(T CoolantInt -T CoolantAct -C1+D1)] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value: T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k),(T CoolantAct -T CoolantInt -C1)] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct The actual water temperature is given by f(T), where C1 is the preset temperature value and D1 is the first low temperature threshold. CoolantInt ,k) is the target water temperature correction value, T CoolantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
5. The engine target water temperature control method according to claim 1, characterized in that, When the atmospheric temperature is higher than the second preset temperature; wherein the second preset temperature is higher than the first preset temperature; If the original target water temperature is greater than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, the preset temperature value, and the second low-temperature threshold; wherein, the second low-temperature threshold is less than the first low-temperature threshold. T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k),(T CoolantInt -T CoolantAct -C1-D2)] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value: T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k),(T CoolantAct -T CoolantInt -C1)] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct The actual water temperature is given by f(T), where C1 is the preset temperature value and D2 is the second low temperature threshold. CoolantInt ,k) is the target water temperature correction value, T CoolantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
6. The engine target water temperature control method according to claim 1, characterized in that, When the atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature; If the original target water temperature is higher than the actual water temperature, the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value. T CoolantDsrd =T CoolantInt -min[f(T CoolantInt ,k),(T CoolantInt -T CoolantAct -C1)] If the original target water temperature is not greater than the actual water temperature, then the target water temperature is determined based on the original target water temperature, the adjustment characteristic value of the target water temperature, the actual water temperature, and the preset temperature value: T CoolantDsrd =T CoolantInt +min[f(T CoolantInt ,k),(T CoolantAct -T CoolantInt -C1)] In the formula, T CoolantDsrd For the target water temperature, T CoolantInt The original target water temperature is T, k is the adjustment characteristic value of the target water temperature, and T is the original target water temperature. CoolantAct C1 is the actual water temperature, and f(T) is the preset temperature value. CoolantInt ,k) is the target water temperature correction value, T CoolantInt The larger the value of T, the larger the value of k, and thus f(T) CoolantInt The larger the k), the greater.
7. The engine target coolant temperature control method according to any one of claims 1 to 6, characterized in that, The formula for calculating the adjustment characteristic value of the target water temperature is as follows: In the formula, n is the engine speed, and r Octane f(n,r) is the octane number coefficient of petroleum products. Octane (by n and r) Octane Calibration obtained; phi Knock For the current detonation delay ignition angle, phi KnockMax The maximum ignition angle delayed by detonation, dp MapAct The actual rate of change of gas pressure entering the cylinder. Depend on and dp MapAct Calibration obtained; dM SprkReq To request the rate of change of torque in the fire circuit, T CoolantErr The original target water temperature T CoolantInt Compared with the actual water temperature T CoolantAct The difference, f(dM) SprkReq ,T CoolantErr ) by dM SprkReq and T CoolantErr Calibration obtained; r Adp This is the self-learning correction coefficient.
8. The engine target coolant temperature control method according to claim 7, characterized in that, Self-learning correction coefficient update methods include: If the difference between the target water temperature and the actual water temperature after dynamic optimization exceeds the preset temperature range for more than the first preset time T1 for more than X times in the current driving cycle, and knocking occurs in each of these X occurrences, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and it increases at the first rate K1; and the counter is reset to zero, and it is incremented again in the current driving cycle after the self-learning correction coefficient update learning conditions are met. If the above conditions are not met, and the number of times the difference between the target water temperature after dynamic optimization and the actual water temperature exceeds the preset temperature value C1 for more than the first preset time T1 in the current driving cycle exceeds the preset number N1, and knocking occurs in each of the occurrences within the number X, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and it increases at the second rate; and the counter is reset to zero, and it is accumulated again in the current driving cycle after the self-learning correction coefficient update learning conditions are met. If the above conditions are not met, and the number of times the difference between the target water temperature after dynamic optimization and the actual water temperature exceeds the preset temperature value C1 for more than the first preset time T1 in the current driving cycle exceeds the preset number N1, and knocking does not occur in every occurrence within the number of occurrences X, then the target water temperature self-learning correction coefficient update state is in the upward learning state, and the target water temperature self-learning correction coefficient will not be updated for the time being; and the counter is reset to zero, and will be accumulated again in the current driving cycle after the self-learning correction coefficient update learning conditions are met. If the above conditions are not met, and the difference between the target water temperature after dynamic optimization in the current driving cycle and the actual water temperature does not exceed the preset temperature value C1, then the target water temperature self-learning correction coefficient update state is the downward learning state, and the target water temperature self-learning correction coefficient will not be updated for the time being. If none of the above conditions are met, determine the update status of the target water temperature self-learning correction coefficient in the previous sampling period; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in an upward learning state, then the target water temperature self-learning correction coefficient increases at the third rate K3; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in a downward learning state, then the target water temperature self-learning correction coefficient decreases at the fourth rate K4; if the update status of the target water temperature self-learning correction coefficient in the previous sampling period is in a no-update state, then it remains unchanged; at the same time, in the current sampling period, the update status of the target water temperature self-learning correction coefficient is set to a no-update state. The priority of the above 5 cases decreases from one to the next, and only one case is executed in each sampling period.
9. The engine target water temperature control method according to claim 8, characterized in that, The self-learning correction coefficient updates the learning condition as follows: The fan should be turned on or off within a preset time. The vehicle mileage since the last learning correction coefficient update exceeds the preset mileage value; The atmospheric temperature is not lower than the first preset temperature and not higher than the second preset temperature; If all three conditions above are met simultaneously, then the self-learning correction coefficient update learning condition is satisfied.
10. The engine target water temperature control method according to claim 9, characterized in that, The first preset temperature is -15℃, the second preset temperature is 45℃, the preset temperature value is 2℃, the first low temperature threshold is 0.8℃, the second low temperature threshold is 0.5℃, the preset mileage value is 20,000 kilometers, the preset temperature range is -5℃ to 5℃, the first preset time T1 is 0.5s, the preset number of times N1 is 5, the first rate K1 is 0.03 / 10ms, the second rate is 0.01 / 10ms, the third rate is 0.005 / 10ms, and the fourth rate is -0.003 / 10ms.