A shift strategy optimization method for AT vehicles

Abstract

The present invention discloses a shift strategy optimization method for an AT vehicle, comprising the following steps: step 1, conducting a real vehicle hub fuel consumption test and collecting fuel consumption data; step 2, building a one-dimensional simulation model based on AVL CRUISE software; step 3, setting a vehicle speed V range and a driving wheel end torque T W range, and initialize the engine universal characteristics and external characteristics data as well as the boundary conditions of the one-dimensional simulation model in MATLAB; Step 4, establish a Simulink gear optimization model with MATLAB initialization parameters as input and the fuel-optimal gear as output; Step 5, draw the engine optimal fuel consumption operating condition map based on the Simulink gear optimization model; Step 6, extract the optimal economic shift line from the engine optimal fuel consumption operating condition map under different throttle and vehicle speed conditions, optimize the shift strategy of the AT vehicle, and reduce the fuel consumption of the entire vehicle without increasing the cost of the entire vehicle.

Description

Technical Field

[0001] The present invention belongs to the field of automobiles, and in particular to a shift strategy optimization method for an AT vehicle. Background Art

[0002] Over the past decade, due to the increasing severity of global warming, the international call for energy conservation and environmental protection has become increasingly louder. The country has put forward stricter requirements on automobile energy consumption and emissions, which has promoted the rapid development of new energy vehicles. For fuel vehicles on another track, consumers' requirements for their fuel consumption are also getting higher and higher. Reducing fuel consumption has become an imminent key issue for major traditional car companies. Therefore, major traditional car companies have begun to apply a variety of fuel-saving measures to reduce fuel consumption, such as engine idle start-stop system, battery intelligent charging system, low-friction engine oil, electronic oil pump, etc., but the problem that follows is the rising cost of the entire vehicle. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention provides a shift strategy optimization method for automated transmission (AT) vehicles, reducing overall vehicle fuel consumption without increasing vehicle cost. Using AVL CRUISE, MATLAB, and Simulink software, the present invention optimizes the shift strategy of AT vehicles from a shift strategy perspective, striving to maintain the engine at the optimal combustion point before and after shifts, improving the matching between the engine and transmission, and exploring further opportunities for fuel efficiency improvement. This reduces overall vehicle fuel consumption without increasing vehicle cost, ultimately achieving a lower fuel consumption target.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A method for optimizing a shift strategy of an AT vehicle comprises the following steps:

[0006] Step 1: Conduct a real vehicle hub rotation fuel consumption test and collect fuel consumption data;

[0007] Step 2: Build a one-dimensional simulation model based on AVL CRUISE software;

[0008] Step 3: Set the vehicle speed V range and the drive wheel end torque T W The engine universal and external characteristics data and the boundary conditions of the one-dimensional simulation model are initialized in MATLAB;

[0009] Step 4: Using the MATLAB initialization parameters as input and the fuel consumption optimal gear as output, a Simulink gear optimization model is established;

[0010] Step 5: Draw the engine's optimal fuel consumption operating condition diagram based on the Simulink gear optimization model;

[0011] Step 6: Under different throttle and vehicle speed conditions, the optimal economic shift line is extracted from the engine optimal fuel consumption operating condition map to optimize the shift strategy of the AT vehicle.

[0012] Preferably, in step 2, the boundary conditions of the one-dimensional simulation model and the actual vehicle are determined, and the shift map, fuel cut-off map and pedal map of the actual vehicle are obtained; ensuring that the simulation boundary of the one-dimensional simulation model and the actual vehicle state maintain a unified benchmark.

[0013] Preferably, the actual vehicle boundary conditions in step 2 include the actual vehicle resistance F, curb mass m, and drag coefficient c D , frontal area A, gearbox ratio i g , gearbox efficiency η, final reduction ratio i0 and wheel radius r.

[0014] Preferably, in step 2, the simulated fuel consumption results of the one-dimensional simulation model are compared with the experimental fuel consumption. If the error of the result is within 3%, the shift strategy is optimized based on the one-dimensional simulation model; otherwise, the one-dimensional simulation model is rebuilt until the error of the comparison result between the simulated fuel consumption results of the one-dimensional simulation model and the experimental fuel consumption is within 3%.

[0015] Preferably, in step 3, from the perspective of the entire vehicle, the speed range and the driving wheel end torque range are set, and the engine bench test universal characteristics, engine bench test external characteristics, and gearbox speed ratio i are imported into MATLAB. g , final reduction ratio i0 and engine speed range, and initialize them.

[0016] Preferably, in step 4, the Simulink gear optimization model is based on the set vehicle speed V and drive wheel end torque T W , and combined with the gearbox ratio i g And the main reduction ratio i0, through T E =T W / i g / i0 / 0.95 and N E =V / 0.377 / r×i g ×i0 The two sets of formulas are used to calculate the engine torque T under different gears E and speed N E , then interpolate the universal characteristics of the engine to obtain the corresponding specific fuel consumption under different gears, and compare and select the current vehicle speed V and drive wheel end torque T W The best gear for fuel consumption.

[0017] Preferably, in step 5, an M-file programming language and a Simulink gear optimization model are used to draw an engine optimal fuel consumption operating condition diagram.

[0018] Preferably, in step 6, the gear position G-vehicle speed V-driving wheel torque T is extracted from the engine optimal fuel consumption operating condition map in step 5. W Curve; the driving wheel end torque T W &Vehicle speed V curve through T E =T W / i g / i0 / 0.95 and N E =V / 0.377 / r×i g ×i0 The two sets of formulas are reversed to deduce the corresponding engine torque T E &Speed ​​N E curve; interpolate the pedal map to get the corresponding throttle; combine the gear position G, vehicle speed V, and throttle data to get the optimized shift strategy;

[0019] The optimized shifting strategy is brought into the model for simulation verification of the fuel consumption optimization effect, and the actual vehicle hub fuel consumption test is carried out to verify the optimization effect, thus completing the optimization of the shifting strategy of the AT vehicle.

[0020] Compared with the prior art, the present invention has the following beneficial technical effects:

[0021] This invention provides a shift strategy optimization method for automatic transmission vehicles. Leveraging the powerful matrix operations and data visualization capabilities of MATLAB and Simulink, this method offers a simple plotting method, allowing the fuel economy zones and external characteristics of engines in different gears to be mapped onto a single, intuitive and clearly defined graph. This provides a reliable basis for optimizing the shift strategy. The shift strategy optimization method described in this invention can be implemented during project development, effectively exploring potential fuel efficiency improvements within the shift strategy without increasing project costs, optimizing engine operating conditions, and ultimately achieving fuel efficiency reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Optimize the flow chart for shifting strategy;

[0023] Figure 2 This is a schematic diagram of fuel consumption at different gear ratios;

[0024] Figure 3 This is a schematic diagram of the gear position with the best fuel consumption;

[0025] Figure 4 This is the optimal operating condition map for engine fuel consumption. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0027] The present invention provides a method for optimizing the shift strategy of an AT vehicle, and the main steps are as follows:

[0028] Simulation model construction and benchmarking: Using AVL CRUISE software, a one-dimensional simulation model of an automatic transmission vehicle was constructed. The prototype vehicle's boundary conditions, shift maps, fuel cut-off maps, pedal maps, and other control strategies were obtained from the project to ensure consistency between the simulation model and the test benchmark. The simulation and test fuel consumption values ​​were then benchmarked. Optimization of the shift strategy was then performed, assuming the error was minimal.

[0029] Initialization parameters: From the perspective of the entire vehicle, set the speed range and drive wheel end torque range, import the engine bench test universal characteristics, engine bench test external characteristics, gearbox speed ratio i into MATLAB g , final reduction ratio i0 and engine speed range, and initialize;

[0030] Establish a Simulink gear optimization model: Use MATLAB initialization parameters as input and the gear with optimal fuel consumption as output to establish a Simulink gear optimization model;

[0031] Draw the engine's optimal fuel consumption operating condition diagram: Use the M file programming language and Simulink gear optimization model to draw the engine's optimal fuel consumption operating condition diagram;

[0032] Extract the optimal economic shift line for the vehicle: Under different throttle and vehicle speed conditions, the engine's optimal fuel consumption operating point occurs at different gears. Based on this rule, the optimal economic shift line is extracted from the engine's optimal fuel consumption operating condition map;

[0033] The shift strategy optimization method of the present invention utilizes the powerful matrix operation and data visualization capabilities of MATLAB and Simulink. The drawing method is simple and can fit the fuel consumption economic zones and external characteristics of the engine in different gears on a single graph. The method is intuitive and has clear physical meaning, which can provide a reliable basis for the optimization of the shift strategy of the present invention.

[0034] The shift strategy optimization method described in this invention can be implemented during the project development process. Without increasing the project cost, it can deeply explore the fuel consumption reduction space in the shift strategy, optimize the engine's working state, and achieve the goal of reducing fuel consumption.

[0035] Example

[0036] like Figure 1 As shown, a shift strategy optimization method for an AT vehicle of the present invention comprises the following steps:

[0037] Step 1: Conduct a real vehicle hub fuel consumption test and collect fuel consumption data and other related information;

[0038] Step 2: Based on the data from step 1, including the actual vehicle parameters such as weight, wind resistance, and frontal area, as well as control strategies such as shifting and pedaling, a one-dimensional simulation model is built using AVL CRUISE software.

[0039] Step 3: Confirm the vehicle status and boundary conditions, including the actual vehicle resistance F, curb mass m, and drag coefficient c D , frontal area A, gearbox ratio i g , gearbox efficiency η, final reduction ratio i0, wheel radius r and other information,

[0040] Step 4: Obtain the control strategies for the actual vehicle application, including the shift map, fuel cut-off map, and pedal map. The pedal map structure is shown in Table 1. This ensures that the simulation boundary of the model built in step 2 maintains a consistent benchmark with the actual vehicle state.

[0041] Step 5: Compare the simulated fuel consumption results with the experimental fuel consumption results;

[0042] Step 6: If the error between the simulated fuel consumption result and the experimental fuel consumption result is within 3%, it is considered that the shift strategy optimization can be carried out based on this simulation model; if the error between the simulated fuel consumption result and the experimental fuel consumption result is greater than 3%, execute step 3 to reconfirm the vehicle status and boundary conditions;

[0043] Step 7, determining the engine universal characteristics and external characteristics data;

[0044] Step 8: From the perspective of the entire vehicle, set the vehicle speed V range and the drive wheel end torque T W The engine universal characteristics and external characteristics data in step 7 and the vehicle boundary conditions in step 3 are initialized in MATLAB; the initialization is performed in Matlab, which is similar to inputting these parameters and letting Matlab read and save them. The purpose is to reference these parameters in the subsequent Simulink model optimization shift process. The engine universal characteristics and external characteristics are the engine bench test data used in the actual vehicle and need to be input separately.

[0045] Step 9: Establish a Simulink gear optimization model. The model principle is based on the set vehicle speed V and drive wheel end torque T W , and combined with the gearbox ratio i g And the main reduction ratio i0, through T E =T W / i g / i0 / 0.95 (0.95, transmission efficiency, empirical value) and N E =V / 0.377 / r×i g ×i0 The two sets of formulas are used to calculate the engine torque T under different gears E and speed N E, and then interpolate the universal characteristics of the engine to obtain the corresponding specific fuel consumption under different gears, such as Figure 2 As shown, the current vehicle speed V and the driving wheel end torque T are compared and filtered out. W The gear with the best fuel consumption, such as Figure 3 As shown;

[0046] Step 10: Use the M file programming language and Simulink gear optimization model to draw the engine's optimal fuel consumption operating condition diagram, such as Figure 4 As shown;

[0047] Step 11: Extract the gear position G-vehicle speed V-drive wheel torque T from the engine optimal fuel consumption operating condition map. W curve;

[0048] Step 12: Set the drive wheel end torque T W The corresponding engine torque T is derived by inversely calculating the speed V curve through the two sets of formulas in step 9. E &Speed ​​N E curve;

[0049] Step 13, interpolate the pedal map in step 4 to obtain the corresponding throttle;

[0050] Step 14: Combine the gear position G, vehicle speed V, and throttle data in steps 11 and 13 to obtain an optimized shift strategy, the structure of which is shown in Table 2.

[0051] Step 15: Bring the optimized shift strategy into the model to perform simulation to verify the fuel consumption optimization effect;

[0052] Step 16: If the fuel consumption optimization effect is obvious, the optimized shift strategy is written into the vehicle control strategy, and a real vehicle hub fuel consumption test is carried out to verify the optimization effect, completing the entire shift strategy optimization process.

[0053] Table 1 Pedal Map

[0054]

[0055] Table 2 Gear Shift Map

[0056]

[0057]

Claims

1. A shift strategy optimization method for an AT vehicle, characterized in that: The following steps are included: Step 1: Conduct a real vehicle hub rotation fuel consumption test and collect fuel consumption data; Step 2: Build a one-dimensional simulation model based on AVL CRUISE software; Step 3: Set the speed Range and drive wheel torque The engine universal and external characteristics data and the boundary conditions of the one-dimensional simulation model are initialized in MATLAB; Step 4: Using the MATLAB initialization parameters as input and the fuel consumption optimal gear as output, a Simulink gear optimization model is established; Step 5: Draw the engine's optimal fuel consumption operating condition diagram based on the Simulink gear optimization model; Step 6: Under different throttle and vehicle speed conditions, the optimal economic shift line is extracted from the engine's optimal fuel consumption operating condition map to optimize the shift strategy of the AT vehicle; In step 2, the boundary conditions of the real vehicle of the one-dimensional simulation model are determined, and the shift map, fuel cut-off map, and pedal map of the real vehicle application are obtained; Ensure that the simulation boundary of the one-dimensional simulation model maintains a unified benchmark with the actual vehicle status; In step 4, the Simulink gear optimization model is based on the set vehicle speed. and drive wheel end torque , and combined with the gearbox ratio and the final reduction ratio ,pass and Two sets of formulas calculate the engine torque under different gears and speed , then interpolate the universal characteristics of the engine to obtain the corresponding specific fuel consumption under different gears, and compare and filter out the current speed and drive wheel end torque The gear with the best fuel consumption; In step 6, the gear position is extracted from the engine optimal fuel consumption operating condition map in step 5 -Speed -Drive wheel torque Curve; drive wheel end torque Speed Curve through and The two sets of formulas are used to inversely deduce the corresponding engine torque Speed curve; interpolate the pedal map to get the corresponding throttle; combine the gear , vehicle speed , throttle data, and obtain the optimized shift strategy; the optimized shift strategy is brought into the model for simulation to verify the fuel consumption optimization effect, and the actual vehicle hub fuel consumption test is carried out to verify the optimization effect, thus completing the optimization of the shift strategy for AT vehicles.

2. The method for optimizing the shift strategy of an AT vehicle according to claim 1, characterized in that: The actual vehicle boundary conditions in step 2 include the actual vehicle resistance , curb weight , drag coefficient , windward area , gearbox ratio , gearbox efficiency , main reduction ratio and wheel radius .

3. The method for optimizing the shift strategy of an AT vehicle according to claim 1, wherein: In step 2, the simulated fuel consumption results of the one-dimensional simulation model are compared with the experimental fuel consumption. If the error of the result is within 3%, the shift strategy is optimized based on the one-dimensional simulation model; otherwise, the one-dimensional simulation model is rebuilt until the error of the comparison result between the simulated fuel consumption results of the one-dimensional simulation model and the experimental fuel consumption is within 3%.

4. The method for optimizing the shift strategy of an AT vehicle according to claim 1, wherein: In step 3, from the perspective of the entire vehicle, set the speed range and drive wheel end torque range, import the engine bench test universal characteristics, engine bench test external characteristics, gearbox ratio into MATLAB , main reduction ratio and engine speed range, and initialize it.

5. The method for optimizing the shift strategy of an AT vehicle according to claim 1, wherein: In step 5, the engine optimal fuel consumption operating condition diagram is drawn using the M file programming language and the Simulink gear optimization model.

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