Vehicle control method and device
By calculating the maximum output torque of the engine and sending a torque limit request to the engine management system, the problem of damage to the differential under overload torque is solved, and effective protection of the differential and normal operation of the vehicle is achieved.
Patent Information
- Application Number
- CN202311102528.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-29
- Publication Date
- 2025-02-28
AI Technical Summary
How to protect the differential from damage caused by overload torque, especially when the transmitted torque exceeds the limit.
By calculating the maximum output torque of the engine, according to the extreme input torque of the differential, the engine's inertia torque, the torque converter torque increase, the oil pump loss torque and torque conversion parameters, a torque limit request is sent to the engine management system to control the output torque of the engine, thereby protecting the differential.
Accurate control of the differential is achieved, and the damage to the differential caused by overload torque is avoided, ensuring the normal operation of the vehicle.
Smart Images
Figure CN119532045A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of automobiles, and in particular to a vehicle control method and device. Background Art
[0002] The differential is one of the essential parts of modern automobile drive axles and is a very important part of the vehicle power transmission process. Whether it is a manual transmission or an automatic transmission, a differential is needed. In actual operation, the power of the car is transmitted from the engine to the transmission, and then from the transmission to the differential in the drive axle. The differential can adjust the wheel speed difference between the left and right wheels of the drive axle according to the driving conditions to eliminate the mechanical wear caused by the inconsistent wheel speed of the left and right wheels when turning.
[0003] The ability of a differential to transmit torque is determined according to the design standards of the vehicle and is limited. When the transmitted torque exceeds the limit torque, the differential will break, causing the vehicle to be unable to drive. How to protect the differential is an important issue in this field. Summary of the invention
[0004] To solve the above technical problems, an embodiment of the present application provides a vehicle control method and device, which calculates the maximum output torque of the engine according to the limit input torque of the differential, so as to accurately control the output torque of the engine to control the input torque of the differential, thereby protecting the differential.
[0005] The present application provides a vehicle control method, the method comprising:
[0006] When the actual input torque and the limit input torque of the differential of the vehicle meet the torque limiting condition, determining that the vehicle needs to enter the torque limiting mode;
[0007] The maximum output torque of the engine is calculated according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the torque loss of the oil pump, and the torque conversion parameter between the differential and the transmission, the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter;
[0008] A torque limit request including the maximum output torque is sent to an engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
[0009] Optionally, the calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the oil pump loss torque, and the torque conversion parameter between the differential and the transmission includes:
[0010] Taking the maximum input torque of the transmission as the maximum input torque of the transmission; and
[0011] The difference between the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine and the torque increase of the torque converter is taken as the maximum output torque of the engine.
[0012] Optionally, the torque conversion parameter is the product of the transmission gear ratio and the main reducer speed ratio, the engine inertia torque is the product of the engine's rotational inertia and the engine's speed change rate, and the oil pump loss torque is positively correlated with the engine speed.
[0013] Optionally, when the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition, determining that the vehicle needs to enter the torque limit mode includes:
[0014] When the difference between the limit input torque and the actual input torque of the vehicle's differential is less than a first threshold for a preset time, it is determined that the vehicle needs to enter the torque limit mode, wherein the first threshold is positively correlated with the engine speed and positively correlated with the transmission oil temperature, and the preset time is negatively correlated with the vehicle speed and negatively correlated with the transmission oil temperature.
[0015] Optionally, after sending the torque limit request including the maximum output torque to the engine management system, the method further includes:
[0016] When the actual input torque and the limit input torque of the differential satisfy a torque limit release condition, determining that the vehicle needs to release torque limit;
[0017] A torque limit release request is sent to an engine management system so that the engine management system controls the engine to exit torque limit.
[0018] Optionally, when the actual input torque and the limit input torque of the differential satisfy a torque limit release condition, determining that the vehicle needs to release torque limit includes:
[0019] When the difference between the limit input torque and the actual input torque of the vehicle's differential is greater than a second threshold, it is determined that the vehicle needs to release the torque limit, and the second threshold is positively correlated with the engine speed and the transmission oil temperature.
[0020] Optionally, after determining that the vehicle needs to release the torque limit, the method further includes:
[0021] Determine the target torque for the engine under unlimited torque condition;
[0022] determining a torque recovery time according to a torque difference between the target torque and the actual input torque, and a rotation speed of the engine;
[0023] determining a torque recovery rate of the engine according to the torque recovery time and the difference;
[0024] The torque recovery rate is sent to the engine management system so that the engine management system controls the engine to perform torque recovery based on the torque recovery rate.
[0025] Optionally, the method further includes:
[0026] The limit input torque of the differential is determined according to the wheel speed difference between two wheels connected to the differential, and the limit input torque is negatively correlated with the wheel speed difference.
[0027] An embodiment of the present application provides a vehicle control device, the device comprising:
[0028] A torque limit determination unit, used for determining that the vehicle needs to enter a torque limit mode when the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition;
[0029] a torque calculation unit, for calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the torque loss of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter;
[0030] The torque limit request sending unit is used to send a torque limit request including the maximum output torque to the engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
[0031] Optionally, the torque calculation unit comprises:
[0032] a first calculation unit, configured to use the limit input torque and a ratio of a torque conversion parameter between the differential and the transmission as the maximum input torque of the transmission;
[0033] The second calculation unit is used to take the difference between the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine and the torque increase of the torque converter as the maximum output torque of the engine.
[0034] Optionally, the torque conversion parameter is the product of the transmission gear ratio and the main reducer speed ratio, the engine inertia torque is the product of the engine's rotational inertia and the engine's speed change rate, and the oil pump loss torque is positively correlated with the engine speed.
[0035] Optionally, the torque limit determination unit is specifically used for:
[0036] When the difference between the limit input torque and the actual input torque of the vehicle's differential is less than a first threshold for a preset time, it is determined that the vehicle needs to enter the torque limit mode, wherein the first threshold is positively correlated with the engine speed and positively correlated with the transmission oil temperature, and the preset time is negatively correlated with the vehicle speed and negatively correlated with the transmission oil temperature.
[0037] Optionally, the device further comprises:
[0038] a torque limit release determination unit, configured to determine that the vehicle needs to release torque limit when the actual input torque and the limit input torque of the differential meet a torque limit release condition after the torque limit request including the maximum output torque is sent to the engine management system;
[0039] The torque limit release request sending unit is used to send a torque limit release request to the engine management system so that the engine management system controls the engine to exit the torque limit.
[0040] Optionally, the torque limit release determination unit is specifically used for:
[0041] When the difference between the limit input torque and the actual input torque of the vehicle's differential is greater than a second threshold, it is determined that the vehicle needs to release the torque limit, and the second threshold is positively correlated with the engine speed and the transmission oil temperature.
[0042] Optionally, the device further comprises:
[0043] A target torque determination unit, configured to determine a target torque for the engine in a torque-unrestricted state after determining that the vehicle needs to release the torque restriction;
[0044] a torque recovery time determination unit, configured to determine the torque recovery time according to a torque difference between the target torque and the actual input torque, and a rotation speed of the engine;
[0045] a torque recovery rate determination unit, configured to determine a torque recovery rate of the engine according to the torque recovery time and the difference;
[0046] The rate sending unit is used to send the torque recovery rate to the engine management system, so that the engine management system controls the engine to perform torque recovery based on the torque recovery rate.
[0047] Optionally, the device further comprises:
[0048] The limit input torque determination unit is used to determine the limit input torque of the differential according to the wheel speed difference between two wheels connected to the differential, wherein the limit input torque is negatively correlated with the wheel speed difference.
[0049] The embodiment of the present application provides a vehicle control method and device, when the actual input torque and the limit input torque of the vehicle's differential meet the first condition, it is determined that the vehicle needs to enter the torque-limiting mode, and the maximum output torque of the engine is calculated according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the loss torque of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter, which is equivalent to the engine directly driving the oil pump. Pump, that is to say, a very small part of the output torque of the engine is transmitted to the oil pump, and most of the output torque is transmitted to the transmission after being torque-increased by the torque converter, and the torque input to the transmission is transmitted to the differential, so that the maximum output torque of the engine can be calculated according to the torque transmission route, and the engine working at the maximum output torque can make the differential work in a safe mode, and by sending a torque limit request including the maximum output torque to the engine controller, the engine controller can limit the torque of the engine according to the maximum output torque, thereby accurately controlling the output torque of the engine, thereby accurately controlling the input torque of the differential, and achieving the purpose of protecting the differential. BRIEF DESCRIPTION OF THE DRAWINGS
[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.
[0051] Figure 1 A flow chart of a vehicle control method provided in an embodiment of the present application;
[0052] Figure 2 A schematic diagram of a vehicle power transmission route provided in an embodiment of the present application;
[0053] Figure 3 A torque difference schematic diagram provided in an embodiment of the present application;
[0054] Figure 4 A flowchart of another vehicle control method provided in an embodiment of the present application;
[0055] Figure 5 A schematic diagram of a torque recovery process provided in an embodiment of the present application;
[0056] Figure 6 A structural block diagram of a vehicle control device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0057] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below with reference to the accompanying drawings.
[0058] In the following description, many specific details are set forth to facilitate a full understanding of the present application, but the present application may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.
[0059] The specific implementation of a vehicle control method and device provided by the embodiments of the present application is described in detail below with reference to the accompanying drawings.
[0060] refer to Figure 1 The flowchart of a vehicle control method provided in an embodiment of the present application is shown. The method can be applied to a transmission control unit (TCU) and may include the following steps.
[0061] S101: When the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition, it is determined that the vehicle needs to enter the torque limit mode.
[0062] In the embodiment of the present application, the power can be transmitted from the engine to the transmission, and then from the transmission to the differential. The differential can adjust the wheel speed difference between the left and right wheels of the drive axle according to the driving conditions to eliminate the mechanical wear caused by the inconsistent wheel speeds of the left and right wheels when turning. However, the ability of the differential to transmit torque is determined according to the design standards of the whole vehicle, which is limited. When the transmitted torque exceeds the limit torque, the differential will break, causing the whole vehicle to be unable to drive.
[0063] refer to Figure 2As shown, it is a schematic diagram of a vehicle power transmission route provided by an embodiment of the present application. The engine can output torque, and the output end of the engine can be connected to the input end of the torque converter. Of course, the engine can be connected to the torque converter (TC) through a flywheel. The torque converter is used to achieve torque conversion. The output end of the torque converter can be connected to the input end of the transmission. The input end of the torque converter is connected to the input end of the oil pump, which is equivalent to the engine directly driving the oil pump. A small part of the output torque of the engine is transmitted to the oil pump for driving the oil pump to rotate. Most of the torque is transmitted to the torque converter and then to the transmission. The transmission is used to adjust the driving force and speed of the car in real time. The output end of the transmission is connected to the input end of the differential, so as to control the speed of the left and right axles connected thereto through the differential, and the left axle is connected to the left drive wheel, and the right axle is connected to the right drive wheel, so as to control the wheel speed of the left and right wheels. Among them, the transmission can be a planetary automatic transmission, a dual-clutch automatic transmission, or other types of transmissions, which are not illustrated one by one here.
[0064] The transmission control unit can monitor the actual input torque (N diff ), when the actual input torque of the differential is too large, a torque limit request is sent to the Engine Management System (EMS), thereby controlling the output torque of the engine, and then controlling the input torque of the differential to protect the differential.
[0065] In the process of judging whether the actual input torque of the differential is too large, the judgment can be made based on the limit input torque of the differential. When the actual input torque of the differential and the limit input torque meet the torque limit condition, the actual input torque can be considered to be too large. Among them, the limit input torque is the maximum input torque that the differential can withstand, which is usually related to the real-time working condition of the vehicle, such as the wheel speed difference. The wheel speed difference refers to the difference in wheel speed between the two wheels connected to the differential. The limit input torque is negatively correlated with the wheel speed difference, that is, the larger the wheel speed difference, the smaller the limit input torque can be. Therefore, the limit input torque of the differential can be determined in advance based on the wheel speed difference between the two wheels connected to the differential.
[0066] In actual operation, the limit input torque of the differential under real-time working conditions is usually less than or equal to the maximum torque that the differential can theoretically withstand. The maximum torque that the differential can theoretically withstand is determined during the hardware design phase and has nothing to do with the real-time working conditions. It is the extreme value that the hardware itself can withstand. The limit input torque here is the maximum value controlled by the control strategy, so it is less than or equal to the maximum torque that the differential can theoretically withstand. In addition, the difference between the maximum torque that the differential can theoretically withstand and the limit input torque is positively correlated with the wheel speed difference, that is, the greater the wheel speed difference, the greater the difference between the maximum torque that the differential can theoretically withstand and the limit input torque.
[0067] In the process of determining whether the actual input torque of the differential is too large, the difference (gap) value (N gap ) is less than the first threshold value for a preset time, it is determined that the actual input torque and the limit input torque of the vehicle's differential meet the torque limit condition, and at this time it can be determined that the vehicle needs to enter the torque limit mode. Figure 3 As shown, it is a torque difference schematic diagram provided in an embodiment of the present application. When the difference between the limit input torque of the vehicle's differential and the actual input torque of the vehicle's differential is less than a first threshold value, it means that the actual input torque of the vehicle's differential is closer to the limit input torque. At this time, there is a risk of failure of the differential. The situation where the difference is less than the first threshold value continues for a preset time period, indicating that the duration is long and the risk of failure is greater. Therefore, the vehicle can be torque limited.
[0068] The first threshold value can be determined according to actual conditions. The smaller the first threshold value, the less likely the vehicle is to enter the torque-limiting mode, the lower the safety of the differential, and the less restricted the engine's performance is. The larger the first threshold value, the easier the vehicle is to enter the torque-limiting mode, the higher the safety of the differential, and the more restricted the engine's performance is. Therefore, if the first threshold value is too large, it will affect the engine's power output. If the first threshold value is too small, it will be difficult to effectively protect the differential. The difference between the differential's limit torque and actual torque is usually a positive value. When the difference is compared with the first threshold value, the larger the first threshold value, the easier it is to meet the torque-limiting condition.
[0069] In specific implementation, the first threshold value can be determined according to the engine speed and the transmission oil temperature. The first threshold value can be positively correlated with the engine speed, that is, the higher the engine speed, the larger the first threshold value can be. The first threshold value can be positively correlated with the transmission oil temperature, that is, the higher the transmission oil temperature, the larger the first threshold value can be. The first threshold value under different engine speeds and transmission oil temperatures can be obtained by looking up a table. Refer to Table 1, which is a relationship table reflecting the relationship between the engine speed, the transmission oil temperature and the first threshold value, where the horizontal axis is the engine speed and the vertical axis is the transmission oil temperature.
[0070] Table 1 The first threshold
[0071] Transmission oil temperature\engine speed 200 1000 1500 3000 4400 -10 10 12 16 18 25 0 15 16 19 22 30 80 20 22 26 28 35
[0072] The preset time can be determined according to the actual situation. The longer the preset time is, the less likely the vehicle is to enter the torque-limiting mode, the lower the safety of the differential, and on the contrary, the less restricted the engine's performance is. The shorter the preset time is, the easier it is for the vehicle to enter the torque-limiting mode, the higher the safety of the differential, and on the contrary, the more restricted the engine's performance is. In specific implementation, the preset time can be determined according to the vehicle speed and the transmission oil temperature. The preset time can be negatively correlated with the vehicle speed, that is, the greater the vehicle speed, the smaller the preset time can be. The preset time can be negatively correlated with the transmission oil temperature, that is, the higher the transmission oil temperature, the smaller the preset time can be. The preset time under different vehicle speeds and transmission oil temperatures can be obtained by looking up a table, and no examples are given here.
[0073] S102, calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the loss torque of the oil pump, and the torque conversion parameters between the differential and the transmission.
[0074] In the process of controlling the output torque of the engine, currently the calibration engineers often calibrate based on their experience to determine the maximum output torque as the calibration value, and then control the engine according to the maximum output torque. However, in actual operation, when the calibration value is too low, the engine performance cannot be fully utilized, resulting in weak power and inability to respond to the driver's power needs. When the calibration value is too high, it may cause potential hardware damage risks.
[0075] In order to accurately limit the torque of the engine, in the embodiment of the present application, the maximum output torque of the engine can be calculated according to the power transmission route, that is, from the differential end to the engine end, the losses of the torque converter, the oil pump and the inertia torque are comprehensively considered to calculate the maximum output torque of the engine. According to the power transmission route map of the whole vehicle, it can be known that the output torque of the engine is transmitted to the torque converter and the gearbox in sequence through the flywheel, and then input to the differential. The differential distributes power to both ends to the left and right drive wheels. In addition, the input end of the torque converter is also connected to the input end of the oil pump, which is equivalent to the engine directly driving the oil pump. Therefore, the engine also needs to drive the oil pump to rotate. This process will lose some torque, which is called the oil pump loss torque. The rotational inertia of the engine will also cause some torque loss. The lost torque is recorded as the inertia torque. Therefore, the maximum output torque can be calculated based on the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the oil pump loss torque, and the torque conversion parameters between the differential and the transmission.
[0076] Specifically, the ratio of the limit input torque and the torque conversion parameter between the differential and the transmission can be used as the maximum input torque of the transmission, and the torque conversion parameter can be the transmission assembly speed ratio at the current gear, and the transmission assembly speed ratio at the current gear can be specifically the product of the transmission gear ratio and the final drive ratio. In other words, the maximum input torque of the gearbox = limit input torque / torque conversion parameter = limit input torque / (transmission gear ratio * final drive ratio).
[0077] After determining the maximum input torque of the transmission, the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine, and the difference between the torque increase of the torque converter, can be used as the maximum output torque of the engine, expressed by the following inverse calculation relationship: Maximum output torque of the engine = maximum input torque of the transmission + oil pump loss torque + inertia torque of the engine - torque increase of the torque converter.
[0078] The oil pump loss torque (Pump Torque) can be determined according to the engine speed. The oil pump loss torque can be positively correlated with the engine speed. The two can have a corresponding relationship. The corresponding relationship between the two can be reflected in a relationship table, so that the oil pump loss torque can be obtained by looking up the table according to the engine speed (Engine Speed). Reference Table 2 is a correspondence table between the oil pump loss torque and the engine speed, which can be obtained through bench calibration testing.
[0079] Table 2 Correspondence between oil pump loss torque and engine speed
[0080] Engine Speed 100 500 1500 3000 5000 Pump Torque 3 4 5 6 7
[0081] The inertia torque of the engine can be the product of the rotational inertia of the engine and the rate of change of the engine speed, that is, the inertia torque of the engine = the rotational inertia of the engine J eng *Engine speed change rate a eng .
[0082] The torque converter can play a role in increasing torque. In the process of converting the torque at the differential end to the torque at the engine end, the torque converter needs to increase the torque N. TC Subtracting, the torque converter torque increase can be expressed as: Where K is the torque ratio of the torque converter, which is usually in the range of 0.9-2, and λ B is the torque conversion coefficient of the pump wheel, ρ is the density of the torque converter oil. After the oil type is determined, ρ is also determined accordingly, g is the gravity constant, n B is the impeller speed and D is the effective diameter.
[0083] Through the above calculation method, the maximum output torque of the engine can be calculated according to the limit input torque of the differential, and then the engine can be controlled.
[0084] S103: Sending a torque limit request including the maximum output torque to the engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
[0085] After calculating the maximum output torque of the engine, a torque limit request including the maximum output torque can be sent to the engine management system, so that the engine management system can limit the torque of the engine according to the maximum output torque. Specifically, the engine management system can control the engine to work at the maximum output torque to achieve torque limit on the engine, thereby limiting the actual input torque of the differential and achieving the purpose of protecting the differential.
[0086] refer to Figure 4 As shown, it is a flow chart of another vehicle control method provided by an embodiment of the present application. After the engine is torque-limited, S104 can also be executed to determine that the vehicle needs to release the torque limit when the actual input torque and the limit input torque of the differential meet the torque limit release condition; S105, send a torque limit release request to the engine management system so that the engine management system controls the engine to exit the torque limit. Generally speaking, after the wheel speed difference gradually decreases, the limit input torque of the differential gradually increases, and the difference between the actual input torque and the limit input torque increases accordingly. When the difference increases to a certain extent, it can be determined that the vehicle needs to release the torque limit. Specifically, it can be determined that the vehicle needs to release the torque limit when the difference between the limit input torque and the actual input torque of the vehicle's differential is greater than the second threshold.
[0087] Among them, the second threshold value can be determined according to actual conditions. The larger the second threshold value is, the less likely the vehicle is to exit the torque-limiting mode, the higher the safety of the differential is, and on the contrary, the more limited the performance of the engine is. The smaller the second threshold value is, the easier it is for the vehicle to exit the torque-limiting mode, the lower the safety of the differential is, and on the contrary, the less limited the performance of the engine is. In specific implementation, the second threshold value can be determined according to the engine speed and the transmission oil temperature. The second threshold value can be positively correlated with the engine speed, that is, the higher the engine speed, the larger the second threshold value can be. The second threshold value can be positively correlated with the transmission oil temperature, that is, the higher the transmission oil temperature, the larger the second threshold value can be. The second threshold value under different engine speeds and transmission oil temperatures can be obtained by looking up a table. The second threshold value can be greater than the first threshold value to prevent the vehicle from frequently entering the torque-limiting mode and frequently exiting the torque-limiting mode.
[0088] After determining that the vehicle needs to release the torque limit, the target torque for the engine in the unlimited torque state can also be determined. The target torque can be determined based on the vehicle's control parameters, such as gear information, accelerator pedal information, brake pedal information, etc., so that the engine can recover from the maximum output torque to the target torque.
[0089] After the target torque is determined, the torque recovery time can be determined according to the torque difference between the target torque and the actual input torque and the engine speed, and the engine torque recovery rate (N) can be determined according to the torque recovery time and the torque difference. ramp (Nm / s)), and then send the torque recovery rate to the engine management system, so that the engine management system controls the engine to recover the torque based on the torque recovery rate. Of course, after determining the torque recovery duration, the torque recovery duration can also be sent to the engine management system, so that the engine management system determines the torque recovery rate based on the torque recovery duration, and controls the engine to recover the torque based on the torque recovery rate.
[0090] Among them, if the torque recovery is too fast, it is easy to be impacted, and if the torque recovery is too slow, it will lead to poor power and fail to respond to the driver's needs in time. Therefore, the torque recovery time can be determined according to the torque difference and the engine speed. The torque recovery time is positively correlated with the torque difference, that is, the larger the torque difference, the longer the torque recovery time can be. The torque recovery time is positively correlated with the engine speed, that is, the larger the engine speed, the longer the torque recovery time can be. The torque recovery time can have a corresponding relationship with the engine speed and the torque difference, and the corresponding relationship can be represented by a corresponding relationship table. The torque recovery rate of the engine can be the ratio of the torque difference to the torque recovery time.
[0091] refer to Figure 5 As shown, it is a schematic diagram of a torque recovery process provided by an embodiment of the present application, wherein the horizontal solid line represents the target torque, and after the torque limit end time point, the actual output torque of the engine gradually recovers to the target torque, and after the torque recovery time period, the actual output torque of the engine is recovered, and the recovered actual output torque can be equal to the target torque, or can be a value close to the target torque. The actual output torque can be the maximum output torque of the engine in the torque limit mode, and the torque limit end time point is the time point when the engine torque starts to recover, that is, the time point when the engine management system controls the engine to release the torque limit.
[0092] The embodiment of the present application provides a vehicle control method, when the actual input torque and the limit input torque of the vehicle's differential meet a first condition, it is determined that the vehicle needs to enter a torque-limiting mode, and the maximum output torque of the engine is calculated according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the loss torque of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission and the input end of the oil pump are both connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter, which is equivalent to the engine directly Drive the oil pump, that is, a very small part of the engine's output torque is transmitted to the oil pump, and most of the output torque is transmitted to the transmission after being torque-increased by the torque converter, and the torque input to the transmission is transmitted to the differential. In this way, the maximum output torque of the engine can be calculated according to the torque transmission route, and the engine working at the maximum output torque can make the differential work in a safe mode. By sending a torque limit request including the maximum output torque to the engine controller, the engine controller can limit the torque of the engine according to the maximum output torque, thereby accurately controlling the output torque of the engine, thereby accurately controlling the input torque of the differential, and achieving the purpose of protecting the differential.
[0093] Based on the above vehicle control method, the present application embodiment also provides a vehicle control device, referring to Figure 6 As shown, it is a structural block diagram of a vehicle control device provided in an embodiment of the present application. The device can be applied to a transmission control unit, and the device may include:
[0094] The torque limit determination unit 110 is used to determine that the vehicle needs to enter the torque limit mode when the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition;
[0095] a torque calculation unit 120, for calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the loss torque of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter;
[0096] The torque limit request sending unit 130 is used to send a torque limit request including the maximum output torque to the engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
[0097] Optionally, the torque calculation unit 120 includes:
[0098] a first calculation unit, configured to use the limit input torque and a ratio of a torque conversion parameter between the differential and the transmission as the maximum input torque of the transmission;
[0099] The second calculation unit is used to take the difference between the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine and the torque increase of the torque converter as the maximum output torque of the engine.
[0100] Optionally, the torque conversion parameter is the product of the transmission gear ratio and the main reducer speed ratio, the engine inertia torque is the product of the engine's rotational inertia and the engine's speed change rate, and the oil pump loss torque is positively correlated with the engine speed.
[0101] Optionally, the torque limit determination unit 110 is specifically used for:
[0102] When the difference between the limit input torque and the actual input torque of the vehicle's differential is less than a first threshold for a preset time, it is determined that the vehicle needs to enter the torque limit mode, wherein the first threshold is positively correlated with the engine speed and positively correlated with the transmission oil temperature, and the preset time is negatively correlated with the vehicle speed and negatively correlated with the transmission oil temperature.
[0103] Optionally, the device further comprises:
[0104] a torque limit release determination unit, configured to determine that the vehicle needs to release torque limit when the actual input torque and the limit input torque of the differential meet a torque limit release condition after the torque limit request including the maximum output torque is sent to the engine management system;
[0105] The torque limit release request sending unit is used to send a torque limit release request to the engine management system so that the engine management system controls the engine to exit the torque limit.
[0106] Optionally, the torque limit release determination unit is specifically used for:
[0107] When the difference between the limit input torque and the actual input torque of the vehicle's differential is greater than a second threshold, it is determined that the vehicle needs to release the torque limit, and the second threshold is positively correlated with the engine speed and the transmission oil temperature.
[0108] Optionally, the device further comprises:
[0109] A target torque determination unit, configured to determine a target torque for the engine in a torque-unrestricted state after determining that the vehicle needs to release the torque restriction;
[0110] a torque recovery time determination unit, configured to determine the torque recovery time according to a torque difference between the target torque and the actual input torque, and a rotation speed of the engine;
[0111] a torque recovery rate determination unit, configured to determine a torque recovery rate of the engine according to the torque recovery time and the difference;
[0112] The rate sending unit is used to send the torque recovery rate to the engine management system, so that the engine management system controls the engine to perform torque recovery based on the torque recovery rate.
[0113] Optionally, the device further comprises:
[0114] The limit input torque determination unit is used to determine the limit input torque of the differential according to the wheel speed difference between two wheels connected to the differential, wherein the limit input torque is negatively correlated with the wheel speed difference.
[0115] The embodiment of the present application provides a vehicle control device, which determines that the vehicle needs to enter the torque-limiting mode when the actual input torque and the limit input torque of the vehicle's differential meet the first condition, and calculates the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the loss torque of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission and the input end of the oil pump are both connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter, which is equivalent to the engine directly driving Oil pump, that is to say, a very small part of the output torque of the engine is transmitted to the oil pump, and most of the output torque is transmitted to the transmission and the oil pump after being torque-increased by the torque converter, and the torque input to the transmission is transmitted to the differential, so that the maximum output torque of the engine can be calculated according to the torque transmission route, and the engine working at the maximum output torque can make the differential work in a safe mode, and by sending a torque limit request including the maximum output torque to the engine controller, the engine controller can limit the torque of the engine according to the maximum output torque, thereby accurately controlling the output torque of the engine, thereby accurately controlling the input torque of the differential, and achieving the purpose of protecting the differential.
[0116] Through the description of the above implementation methods, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment method can be implemented by means of software plus a general hardware platform. Based on such an understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods described in each embodiment of the present application or some parts of the embodiments.
[0117] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.
[0118] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.
[0119] The above is only a preferred implementation of the present application. Although the present application has been disclosed as a preferred embodiment, it is not intended to limit the present application. Any technician familiar with the art can use the above disclosed methods and technical contents to make many possible changes and modifications to the technical solution of the present application without departing from the scope of the technical solution of the present application, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application still falls within the scope of protection of the technical solution of the present application.
Claims
1. A vehicle control method, characterized in that: The method comprises: When the actual input torque and the limit input torque of the differential of the vehicle meet the torque limiting condition, determining that the vehicle needs to enter the torque limiting mode; The maximum output torque of the engine is calculated according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the torque loss of the oil pump, and the torque conversion parameter between the differential and the transmission, the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter; A torque limit request including the maximum output torque is sent to an engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
2. The method according to claim 1, characterized in that The calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the oil pump loss torque and the torque conversion parameter between the differential and the transmission comprises: Taking the maximum input torque of the transmission as the maximum input torque of the transmission; and The difference between the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine and the torque increase of the torque converter is taken as the maximum output torque of the engine.
3. The method according to claim 2, characterized in that The torque conversion parameter is the product of the transmission gear ratio and the main reducer ratio, the inertia torque of the engine is the product of the rotational inertia of the engine and the speed change rate of the engine, and the oil pump loss torque is positively correlated with the speed of the engine.
4. The method according to any one of claims 1 to 3, characterized in that: When the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition, determining that the vehicle needs to enter the torque limit mode includes: When the difference between the limit input torque and the actual input torque of the vehicle's differential is less than a first threshold for a preset time, it is determined that the vehicle needs to enter the torque limit mode, the first threshold is positively correlated with the engine speed and positively correlated with the transmission oil temperature, and the preset time is negatively correlated with the vehicle speed and negatively correlated with the transmission oil temperature.
5. The method according to any one of claims 1 to 3, characterized in that: After sending the torque limit request including the maximum output torque to the engine management system, the method further includes: When the actual input torque and the limit input torque of the differential satisfy a torque limit release condition, determining that the vehicle needs to release torque limit; A torque limit release request is sent to an engine management system so that the engine management system controls the engine to exit torque limit.
6. The method according to claim 5, characterized in that When the actual input torque and the limit input torque of the differential satisfy the torque limit release condition, determining that the vehicle needs to release the torque limit includes: When the difference between the limit input torque and the actual input torque of the vehicle's differential is greater than a second threshold, it is determined that the vehicle needs to release the torque limit, and the second threshold is positively correlated with the engine speed and the transmission oil temperature.
7. The method according to claim 5, characterized in that After determining that the vehicle needs to release the torque limit, the method further includes: Determine the target torque for the engine under unlimited torque condition; determining a torque recovery time according to a torque difference between the target torque and the actual input torque, and a rotation speed of the engine; determining a torque recovery rate of the engine according to the torque recovery time and the difference; The torque recovery rate is sent to the engine management system so that the engine management system controls the engine to perform torque recovery based on the torque recovery rate.
8. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: The limit input torque of the differential is determined according to the wheel speed difference between two wheels connected to the differential, and the limit input torque is negatively correlated with the wheel speed difference.
9. A vehicle control device, characterized in that: The device comprises: A torque limit determination unit, used for determining that the vehicle needs to enter a torque limit mode when the actual input torque and the limit input torque of the differential of the vehicle meet the torque limit condition; a torque calculation unit, for calculating the maximum output torque of the engine according to the limit input torque, the inertia torque of the engine, the torque increase of the torque converter, the torque loss of the oil pump, and the torque conversion parameter between the differential and the transmission, wherein the input end of the torque converter is connected to the output end of the engine, the output end of the transmission is connected to the input end of the differential, the input end of the transmission is connected to the output end of the torque converter, and the input end of the oil pump is connected to the input end of the torque converter; The torque limit request sending unit is used to send a torque limit request including the maximum output torque to the engine management system, so that the engine management system limits the torque of the engine according to the maximum output torque.
10. The device according to claim 9, characterized in that The torque calculation unit comprises: a first calculation unit, configured to use the limit input torque and a ratio of a torque conversion parameter between the differential and the transmission as the maximum input torque of the transmission; The second calculation unit is used to take the difference between the sum of the maximum input torque of the transmission, the oil pump loss torque and the inertia torque of the engine and the torque increase of the torque converter as the maximum output torque of the engine.