Method for determining minimum speed of vehicle sliding in neutral gear

Abstract

The invention relates to a method for determining the minimum speed of a vehicle sliding in a neutral gear. The vehicle sliding in the neutral gear comprises the steps that the vehicle resistance is calculated according to sliding resistance; obtaining the distance, the vehicle speed and the time of neutral gear sliding; calculating the idling oil consumption in the whole sliding process; the whole vehicle resistance is calculated according to the sliding resistance; calculating a corresponding gear and a corresponding rotating speed according to the vehicle speed; calculating the push-pull torque according to the engine speed, and correcting the resistance; obtaining the sliding distance with the gear and the corresponding vehicle speed; a, after data in the steps S3 and S33 are collected, the fuel consumption G1 per hundred kilometers when neutral gear sliding is longer than gear sliding by a sliding distance is calculated; b, compared with fuel consumption G2 per hundred kilometers under common working conditions, G1 is smaller than G2; c, when the requirement B is met, the current vehicle speed can enter a neutral gear for sliding; and D, if the B requirement is not met, the current vehicle speed can slide with a gear. According to the method for determining the minimum speed of the vehicle entering the neutral gear for sliding, the fuel economy of the heavy commercial vehicle is improved, and the energy consumption is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle control, and in particular to a method for determining the minimum vehicle speed for entering neutral coasting. Background Art

[0002] With the continuous progress of society, the transportation industry has developed rapidly. In the transportation industry, commercial vehicles, especially heavy-duty AMT commercial vehicles, are often used. At present, the fuel consumption of heavy-duty AMT commercial vehicles is relatively high during use. Neutral coasting, as a control method during vehicle driving, is an important fuel-saving mode in the AMT transmission and contributes greatly to fuel saving. However, no one has clearly studied the minimum vehicle speed for entering the neutral coasting function after releasing both the throttle and the brake on a flat road. When coasting in gear, the kinetic energy of the whole vehicle drags the engine backward, and the fuel injection volume is 0 L / h at this time, but the coasting distance is short; when coasting in neutral, the clutch is in the closed state but the shift fork is in neutral, and the engine enters the idle state and only overcomes the friction work and oil agitation loss, and the fuel injection volume is about 1.7 L / h (for a 13-liter engine), and the neutral coasting distance is long. When the vehicle speed is lower than what value, it is not suitable to enter the neutral coasting function anymore. Such problems urgently need to be solved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is: In order to solve the problems existing in the above background art, a method for determining the minimum vehicle speed for entering neutral coasting is provided. By establishing an AMT model, based on the vehicle parameters and boundary conditions, the coasting distances, vehicle speeds, and fuel consumptions of neutral coasting and coasting in gear are calculated to provide a reference for the driver, improve the fuel economy of heavy-duty commercial vehicles, and reduce energy consumption.

[0004] The technical solution adopted by the present invention to solve its technical problems is: A method for determining the minimum vehicle speed for entering neutral coasting of a vehicle includes the following steps: When the vehicle coasts in neutral, S1. Calculate the vehicle resistance according to the coasting resistance; S2. Obtain the coasting distance, vehicle speed, and time of neutral coasting; S3. Calculate the idle fuel consumption during the entire coasting process; When the vehicle coasts in gear, S11. Calculate the vehicle resistance according to the coasting resistance;

[0005] S22. Calculate the corresponding gear and corresponding rotational speed according to the vehicle speed; S33. Calculate the drag torque according to the engine rotational speed and correct the resistance; S44. Obtain the coasting distance and the corresponding vehicle speed of coasting in gear;

[0006] A. After collecting the data in S3 and S33, calculate the fuel consumption per 100 kilometers G1 of the extra distance coasted in neutral compared to coasting in gear; B. Compare it with the fuel consumption per 100 kilometers G2 under normal working conditions, G1 < G2; C. When the requirement of B is met, the current vehicle speed can enter neutral coasting; D. When the requirement of B is not met, the current vehicle speed can coast in gear.

[0007] Further elaboration is as follows. In the above technical solution, the calculation formula for the total vehicle resistance in S1 is F = A + B*v + C*v 2 ; where F: total vehicle resistance; A: rolling resistance; B: aerodynamic resistance; C: internal resistance of the whole vehicle; V: speed; the calculation formula for the total vehicle resistance in S11 is F = A + B*v + C*v 2 +F 1 ; where F: total vehicle resistance; A: rolling resistance; B: aerodynamic resistance; C: internal resistance of the whole vehicle; V: speed; F 1 : resistance generated by the engine drag torque.

[0008] Further elaboration is as follows. In the above technical solution, the calculation formula for the idle fuel consumption during the entire coasting process in S3 is: L_idle = 1.7*t; where L_idle: idle fuel consumption; t: idle time.

[0009] Further elaboration is as follows. In the above technical solution, the calculation formula for the vehicle speed in S2 and S44 is V = w / igear / i_rear axle*Π / 30*R; where V: vehicle speed; w: engine speed in rpm; igear: gear ratio of each gear; i_rear axle: rear axle ratio; R: tire radius.

[0010] Further elaboration is as follows. In the above technical solution, the calculation formulas for the coasting distance in neutral and the coasting distance in gear in S2 and S44 are both where S: distance; a: acceleration; t: coasting time; V 初 : vehicle speed when starting to coast in neutral or in gear.

[0011] The beneficial effects of the present invention are as follows: A method for determining the minimum vehicle speed for entering neutral coasting is proposed in the present invention. By establishing an AMT model and based on the vehicle parameters and boundary conditions, the coasting distances, vehicle speeds, and fuel consumptions of neutral coasting and coasting in gear are calculated, providing a reference for the driver, improving the fuel economy of heavy commercial vehicles, and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings described below are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0013] Figure 1 is the flow diagram of the present invention;

[0014] Figure 2It is a graph showing the relationship between the sliding distance and the starting speed in the present invention. Specific embodiments

[0015] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0016] In this application, assuming that the vehicle speed at this moment is V, the vehicle's sliding resistance is calculated according to the ABC values (including rolling resistance, wind resistance and internal resistance of the whole vehicle) obtained from the sliding test on the test field, and then the vehicle's deceleration is obtained. According to the vehicle's deceleration, the vehicle speed at the next moment is obtained until the vehicle speed slides to 5 km / h and ends. The sliding distance and time are calculated, and the total idle fuel consumption is calculated. The resistance generated by the engine's drag torque is more in coasting with gear than in neutral coasting. This resistance needs to consider the gear ratio and the rear axle ratio to be converted into the vehicle's resistance. In addition, during the process of coasting with gear, as the vehicle speed decreases and the engine speed is lower than the idle speed, downshifting is required. During the downshifting process, the engine needs to inject fuel to adjust the engine speed. Similarly, according to the vehicle's resistance, the deceleration is calculated to obtain the vehicle speed at the next moment until the vehicle speed slides to 5 km / h and ends. The sliding distance and time are calculated, the number of gearshifts is counted, and the fuel injection amount consumed during gearshift is calculated. The difference between the two mileage and the difference in fuel consumption are calculated to obtain the fuel consumption per 100 km G1 for the additional sliding distance, and then compared with the fuel consumption per 100 km G2 under normal working conditions.

[0017] Establish a vehicle AMT model in cruise, establish coasting (neutral coasting without gear) and engine braking (coasting with gear) in the task list, set the ground friction coefficient to 1; set the wind speed to 0; set the slope to 0; set the gearshift time to 1.2 s; set the efficiency of the rear axle differential to 1; set the vehicle to the hot start state; the initial gear during coasting with gear is executed according to the AMT gearshift line, and the other vehicle parameters are filled in according to the parameters in Table 1.

[0018]

[0019] Table 1

[0020] See Figure 1 and Figure 2 What is shown is a method for determining the minimum vehicle speed for entering neutral coasting, including the following steps:

[0021] When the vehicle is in neutral coasting, S1: Calculate the vehicle's resistance according to the sliding resistance; S2: Obtain the sliding distance, vehicle speed and time of neutral coasting; S3: Calculate the idle fuel consumption during the entire sliding process;

[0022] When the vehicle coasts in gear, S11. Calculate the vehicle resistance according to the coasting resistance; S22. Calculate the corresponding gear and corresponding speed according to the vehicle speed; S33. Calculate the drag torque according to the engine speed and correct the resistance; S44. Obtain the coasting distance in gear and the corresponding vehicle speed.

[0023] A. After collecting the data in S3 and S33, calculate the fuel consumption per 100 kilometers G1 of the additional distance coasted in neutral compared to coasting in gear; B. Compare with the fuel consumption per 100 kilometers G2 under normal operating conditions, G1 < G2; C. If the requirement in B is met, the current vehicle speed can enter neutral coasting; D. If the requirement in B is not met, the current vehicle speed can coast in gear.

[0024] Among them, the calculation formula for the vehicle resistance in S1 is F = A + B * v + C * v 2 ; where F: vehicle resistance; A: rolling resistance; B: air resistance; C: internal resistance of the vehicle; V: speed; the calculation formula for the vehicle resistance in S11 is F = A + B * v + C * v 2 + F 1 ; where F: vehicle resistance; A: rolling resistance; B: air resistance; C: internal resistance of the vehicle; V: speed; F 1 : the resistance generated by the engine drag torque. The calculation formula for the fuel consumption during idling in the entire coasting process in S3 is: L_idle = 1.7 * t; where L_idle: idling fuel consumption; t: idling time. The calculation formula for the vehicle speed in S2 and S44 is V = w / igear / i_rear axle * Π / 30 * R; where V: vehicle speed; w: engine speed rpm; igear: gear ratio of each gear; i_rear axle: rear axle ratio; R: tire radius. The calculation formulas for the coasting distance in neutral and the coasting distance in gear in S2 and S44 are both where S: distance; a: acceleration; t: coasting time; V 初 : the vehicle speed when starting to enter neutral coasting or coasting in gear.

[0025] In this application, when coasting at different vehicle speeds, the program can calculate whether it is good or not to enter coasting at this vehicle speed. Table 2 shows the corresponding fuel consumption G1 for entering coasting at different vehicle speeds under the current vehicle configuration. It can be seen from the table that when the vehicle speed is 35 km / h and enters coasting, the G1 fuel consumption is higher than 30 L / 100 km. At this time, it is not appropriate to enter coasting again. Therefore, the critical vehicle speed for this tractor to enter neutral coasting should be 35 km / h.

[0026] Serial number Vehicle speed for entering coasting (km / h) Fuel consumption per 100 km for neutral coasting with more distance coasted than in-gear coasting, G1 1 60 18.8 L / 100 km 2 50 21.06 L / 100 km 3 40 24.43 L / 100 km 4 35 30.88 L / 100 km

[0027] Table 2

[0028] In this application, the engine speed limit is 600 - 1900 rpm; the corresponding torque Nm relationship is as shown in Table 3 below.

[0029] Revolutions per minute (rpm) Torque (Nm) 600 -103.1 700 -107.7 800 -115.2 900 -123.5 1000 -132.9 1100 -143.5 1200 -155 1300 -168 1400 -181 1500 -195.2 1600 -211.2 1700 -228.9 1800 -247.3 1900 -267.5

[0030] Table 3

[0031] Beneficial effects of the present invention: In the neutral coasting function of the AMT gearbox, the minimum vehicle speed for entering neutral coasting can be calculated. The present invention can determine this minimum coasting vehicle speed under the assumption that some boundary conditions are fixed. The determination of the minimum neutral coasting vehicle speed is related to the following parameters, including the vehicle speed at the end of coasting, the drag torque during engine reverse drag, the vehicle rolling coefficient, the air resistance coefficient, the frontal area, the tire radius, the rear axle ratio, the vehicle weight, and the gear ratio corresponding to the gear during gear coasting. Here, assume the vehicle speed when entering coasting is V1, the vehicle speed at the end of coasting is V2, the neutral coasting distance is S1, the gear coasting distance is S2, the fuel consumption during neutral coasting from V1 to V2 is L1, the fuel consumption during gear coasting from V1 to V2 is L2, the additional distance that neutral coasting slides more than gear coasting is H, calculate the fuel consumption per 100 kilometers of the additional distance that neutral coasting slides more than gear coasting as G1, and compare G1 with the total fuel consumption per 100 kilometers G2 of this vehicle on this road. For example, the high-speed fuel consumption G2 of a 49-ton tractor is about 30L / 100km. If G1 is greater than 30L / 100km, then this V1 is not suitable for entering neutral coasting. If G1 is less than 30L / 100km, then this V1 is suitable for entering neutral coasting.

[0032] The above-mentioned is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.

Claims

1. A method for determining the minimum vehicle speed for a vehicle to enter neutral and coast, characterized in that: It includes the following steps: When the vehicle coasts in neutral, S1. Calculate the vehicle resistance according to the coasting resistance; S2. Obtain the coasting distance, vehicle speed and time in neutral; S3. Calculate the fuel consumption at idle during the entire coasting process; When the vehicle coasts in gear, S11. Calculate the vehicle resistance according to the coasting resistance; S22. Calculate the corresponding gear and corresponding rotational speed according to the vehicle speed; S33. Calculate the drag torque according to the engine speed and correct the resistance; S44. Obtain the coasting distance in gear and the corresponding vehicle speed; A. After collecting the data in S3 and S33, calculate the fuel consumption per 100 kilometers G1 for the extra distance coasted in neutral compared to coasting in gear; B. Compare with the fuel consumption per 100 kilometers G2 under normal operating conditions, G1 < G2; C. If the requirement in B is met, the current vehicle speed can enter neutral coasting; D. If the requirement in B is not met, the current vehicle speed can coast in gear.

2. The method for determining the minimum vehicle speed for coasting in neutral according to claim 1, characterized in that: The calculation formula of the S1 vehicle resistance is F = A + B*v + C*v 2 ; Where F: vehicle resistance; A: rolling resistance; B: wind resistance; C: vehicle internal resistance; V: speed; the calculation formula of vehicle resistance in S11 is F=A+B*v+C*v 2 +F1; where F is the vehicle resistance; A is rolling resistance; B is wind resistance; C: Internal resistance of the vehicle; V: Speed; F1: Resistance generated by the engine drag torque.

3. The method for determining the minimum vehicle speed for coasting in neutral according to claim 1, characterized in that: The calculation formula for the fuel consumption at idle during the entire coasting process in S3 is: L_idle = 1.7 * t; where L_idle: Idle fuel consumption; t: Idle time.

4. The method for determining the minimum vehicle speed for coasting in neutral according to claim 1, characterized in that: The calculation formula for the vehicle speed in S2 and S44 is: V = w / igear / i_rear axle * Π / 30 * R; where V: Vehicle speed; w: Engine speed in rpm; igear: Gear ratio of each gear; i_rear axle: Rear axle ratio; R: Tire radius.

5. The method for determining the minimum vehicle speed for coasting in neutral according to claim 1, characterized in that: The calculation formulas for the neutral coasting distance and the gear-engaged coasting distance in S2 and S44 are: Where S: distance; a: acceleration; t: sliding time; V 初 : The vehicle speed at which it starts to coast in neutral or with a gear.

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