Motor torque control method of electric vehicle

Abstract

The invention provides a motor torque control method for an electric vehicle, which comprises the following steps of: when an electric drive axle of the vehicle has a backlash, acquiring vehicle state information; judging the vehicle state information, and matching a motor torque control strategy corresponding to the vehicle state information; and based on the motor torque control strategy, the motor torque of the electric drive axle is adjusted to reduce the backlash of the electric drive axle, so that the backlash of the whole electric drive axle assembly can be engaged in advance, the service life of a gear is prolonged, and inter-tooth impact, tooth beating and abnormal sound are avoided when the vehicle is started and decelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle control, and in particular to a motor torque control method for an electric vehicle. Technical Background

[0003] The electric drive axle is a product that combines the motor and the axle, realizing the power transmission after electrification, and has the characteristics of high transmission efficiency and good endurance performance. The motor and the axle of the electric drive axle are transmitted through a reducer, which includes a driving gear, a driven gear and a rack. Through gear meshing, the movement and power of the driving gear are transmitted to the driven wheel to obtain the required speed and torque.

[0004] In gear meshing transmission, in order to form a lubricating oil film between the meshing tooth profiles and avoid the gears from getting stuck due to friction, heat and expansion, there must be a gap between the tooth profiles. This gap is called the tooth side clearance, or side clearance for short. Since the entire axle is a transmission chain composed of multiple sets of gears, there are multiple side clearances in the entire electric drive axle.

[0005] Existing vehicles do not have a procedure for early gear meshing during starting, deceleration, and reverse gearing. When the vehicle is in this working condition, due to the existence of side clearance, the starting torque is large, which will instantly produce a large impact between the teeth, resulting in tooth knocking and abnormal noise, and abnormal vehicle shaking. It can be seen that the existing products have poor starting, deceleration, and reverse gear smoothness, and the main reduction gear has a short life. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the motor torque control method of an electric vehicle in the prior art, so that the side clearance of the entire electric drive axle assembly can be engaged in advance when the vehicle starts or decelerates, thereby improving the life of the gears, avoiding impact between teeth, and avoiding tooth knocking and abnormal noise.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for controlling the motor torque of an electric vehicle comprises the following steps:

[0009] S100, when there is side play on the electric drive axle of the vehicle, obtaining vehicle status information;

[0010] S200, judging the vehicle state information, and matching the motor torque control strategy corresponding to the vehicle state information;

[0011] S300: Based on the motor torque control strategy, adjust the motor torque of the electric drive bridge to reduce the side clearance of the electric drive bridge.

[0012] As a preferred embodiment, the vehicle status information includes gear information and working condition information, and the step S200 includes the following steps:

[0013] S210, determining a judgment condition according to the gear information;

[0014] S220: judging the operating condition information based on the judgment condition, and matching the motor torque control strategy corresponding to the operating condition information.

[0015] As a preferred embodiment, the step S210 includes the following steps:

[0016] S211, if the gear information is D gear, make a judgment based on the first judgment condition;

[0017] S212: If the gear information is R gear, make a judgment based on the second judgment condition.

[0018] As a preferred embodiment, the step S211 includes the following steps:

[0019] Determine whether the operating condition information meets the first condition, and if so, execute the first strategy and determine it as a normal operating condition;

[0020] If not, determine whether the operating condition information meets the second condition; if yes, execute the second strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

[0021] As a preferred embodiment, step S212 includes the following steps:

[0022] Determine whether the operating condition information meets the third condition, and if so, execute the third strategy and determine it as a normal operating condition;

[0023] If not, determine whether the operating condition information meets the fourth condition; if yes, execute the fourth strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

[0024] As a preferred embodiment, the operating condition information includes vehicle status information, motor speed, axle speed, and throttle information.

[0025] As a preferred embodiment, the first condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists;

[0026] The first strategy includes the motor torque being 1 N.m and the input time being 0.1 s.

[0027] As a preferred embodiment, the second condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal;

[0028] The second strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

[0029] As a preferred embodiment, the third condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists;

[0030] The third strategy includes the motor torque being -1 N.m and the input time being 0.1 s.

[0031] As a preferred embodiment, the fourth condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal;

[0032] The fourth strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

[0033] Compared with the prior art, this technical solution has the following advantages:

[0034] When the vehicle starts or decelerates, the side clearance of the entire electric drive axle assembly can be engaged in advance, thereby increasing the life of the gears, avoiding impact between teeth, and avoiding tooth knocking and abnormal noise.

[0035] The present invention is further described below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the motor torque control method of the electric vehicle according to the present invention;

[0037] Figure 2 The block diagram is a motor torque control method for an electric vehicle according to the present invention. DETAILED DESCRIPTION

[0038] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles of the present invention defined in the following description can be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not deviate from the spirit and scope of the present invention.

[0039] like Figure 1 and Figure 2 As shown, the motor torque control method of the electric vehicle comprises the following steps:

[0040] S100, when there is side play on the electric drive axle of the vehicle, obtaining vehicle status information;

[0041] S200, judging the vehicle state information, and matching the motor torque control strategy corresponding to the vehicle state information;

[0042] S300: Based on the motor torque control strategy, adjust the motor torque of the electric drive bridge to reduce the side clearance of the electric drive bridge.

[0043] Different motor torque control strategies are formulated based on different vehicle status information, so that the side clearance of the electric drive axle can be reduced under different vehicle status information, so that the electric drive axle can enter the gear meshing state in advance, and the motor will then output normal torque, which will extend the vehicle life and improve the vehicle's driving stability.

[0044] like Figure 1 As shown, in step S100, there is a side clearance between the meshing gears of the electric drive axle, which is used to form a lubricating oil film to prevent the gear teeth from getting stuck due to friction, heat and expansion. Specifically, when the vehicle starts and decelerates, the electric drive axle will have a side clearance.

[0045] The vehicle status information includes gear information and working condition information. The gear information includes D gear and R gear, wherein D gear (forward gear) is a gear designed for normal vehicle driving, and R gear (reverse gear) is a gear designed for reverse operation. The working condition information includes vehicle status information, motor speed, axle speed, and throttle information. The vehicle status information includes two states: starting and deceleration. The motor speed refers to the speed of rotation when the motor is in action, and the axle speed refers to the rotation speed of the wheel, that is, the motor speed is the input speed, and the axle speed is the output speed. The throttle information includes whether the accelerator pedal is pressed. If it is pressed, there is a throttle signal, and if it is not pressed, there is no throttle signal.

[0046] like Figure 2 As shown, the vehicle status information includes gear information and working condition information, and the step S200 includes the following steps:

[0047] S210, determining a judgment condition according to the gear information;

[0048] S220: judging the operating condition information based on the judgment condition, and matching the motor torque control strategy corresponding to the operating condition information.

[0049] The different gear information will result in different judgment conditions, and thus different motor torque control strategies will be matched to achieve a comprehensive strategic layout, in order to avoid gear side clearance, gear knocking, abnormal noise, etc. during vehicle operation, thereby increasing the life of the gears.

[0050] refer to Figure 2 , the step S210 comprises the following steps:

[0051] S211, if the gear information is D gear, make a judgment based on the first judgment condition;

[0052] S212: If the gear information is R gear, make a judgment based on the second judgment condition.

[0053] If the rear gear information is neither D gear nor R gear, the vehicle is directly determined to be in normal operating condition. For example, the vehicle is in P gear (parking gear) or N gear (neutral gear) at this time, and the motor does not need to run. There is no abnormal noise due to side clearance of the gears, and the vehicle is then determined to be in normal operating condition.

[0054] refer to Figure 2 , the step S211 comprises the following steps:

[0055] Determine whether the operating condition information meets the first condition, and if so, execute the first strategy and determine it as a normal operating condition;

[0056] If not, determine whether the operating condition information meets the second condition; if yes, execute the second strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

[0057] The first condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists.

[0058] The first strategy includes the motor torque being 1 N.m and the input time being 0.1 s.

[0059] The second condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal.

[0060] The second strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

[0061] The motor torque in the first strategy is positive torque, and the motor torque in the second strategy is negative torque. The positive torque and the negative torque are torques with different directions. When the direction of the torque is consistent with the rotation direction of the object (or the rotation direction of the wheel), the torque is called positive torque, and when the direction of the torque is opposite to the rotation direction of the object (or the rotation direction of the wheel), the torque is called negative torque.

[0062] refer to Figure 2 , the step S212 comprises the following steps:

[0063] Determine whether the operating condition information meets the third condition, and if so, execute the third strategy and determine it as a normal operating condition;

[0064] If not, determine whether the operating condition information meets the fourth condition; if yes, execute the fourth strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

[0065] The third condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists.

[0066] The third strategy includes the motor torque being -1 N.m and the input time being 0.1 s.

[0067] The fourth condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal.

[0068] The fourth strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

[0069] In step S300, according to the motor torque control strategy, the corresponding motor torque is selected to reduce the side clearance of the gear of the electric drive axle, thereby ensuring that the gear is protected from impact force during subsequent operation of the electric drive axle, thereby increasing the life of the gear, reducing abnormal noise, and ensuring smooth vehicle driving.

[0070] In summary, when the vehicle starts and decelerates, the side clearance of the entire electric drive axle assembly can be engaged in advance, which improves the life of the gears, avoids impact between teeth, and avoids gear knocking and abnormal noise. When the vehicle speed changes from 0 to non-0, the motor first eliminates the side clearance of the teeth with a torque of 1N.m within 0.1S, and then increases the torque normally to make the gears engage in advance, so that the vehicle can start and decelerate smoothly.

[0071] The embodiments described above are only used to illustrate the technical ideas and features of the present invention, and their purpose is to enable technicians in this field to understand the content of the present invention and implement it accordingly. The patent scope of the present invention cannot be limited only by this embodiment, that is, any equivalent changes or modifications made according to the spirit disclosed by the present invention still fall within the patent scope of the present invention.

Claims

1. A motor torque control method for an electric vehicle, characterized in that: The following steps are involved: S100, when there is side play on the electric drive axle of the vehicle, obtaining vehicle status information; S200, judging the vehicle state information, and matching the motor torque control strategy corresponding to the vehicle state information; S300: Based on the motor torque control strategy, adjust the motor torque of the electric drive axle to reduce the side clearance of the electric drive axle.

2. The motor torque control method of an electric vehicle according to claim 1, characterized in that: The vehicle status information includes gear information and operating condition information, and the step S200 includes the following steps: S210, determining a judgment condition according to the gear information; S220: judging the operating condition information based on the judgment condition, and matching the motor torque control strategy corresponding to the operating condition information.

3. The motor torque control method of an electric vehicle as claimed in claim 2, characterized in that: The step S210 includes the following steps: S211, if the gear information is D gear, make a judgment based on the first judgment condition; S212: If the gear information is R gear, make a judgment based on the second judgment condition.

4. The motor torque control method of an electric vehicle as claimed in claim 3, characterized in that: The step S211 comprises the following steps: Determine whether the operating condition information meets the first condition, and if so, execute the first strategy and determine it as a normal operating condition; If not, determine whether the operating condition information meets the second condition; if yes, execute the second strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

5. The motor torque control method of an electric vehicle as claimed in claim 3, characterized in that: The step S212 comprises the following steps: Determine whether the operating condition information meets the third condition, and if so, execute the third strategy and determine it as a normal operating condition; If not, determine whether the operating condition information meets the fourth condition; if yes, execute the fourth strategy and determine it as a normal operating condition; if not, directly determine it as a normal operating condition.

6. The motor torque control method of an electric vehicle as claimed in claim 5, characterized in that: The operating condition information includes vehicle status information, motor speed, axle speed, and throttle information.

7. The motor torque control method of an electric vehicle as claimed in claim 6, characterized in that: The first condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists; The first strategy includes the motor torque being 1 N.m and the input time being 0.1 s.

8. The motor torque control method of an electric vehicle as claimed in claim 6, characterized in that: The second condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal; The second strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

9. The motor torque control method of an electric vehicle as claimed in claim 6, characterized in that: The third condition includes that the vehicle state information is starting, the motor speed is 0, the axle speed is 0, and the throttle information is that a throttle signal exists; The third strategy includes the motor torque being -1 N.m and the input time being 0.1 s.

10. The motor torque control method of an electric vehicle as claimed in claim 6, characterized in that: The fourth condition includes that the vehicle state information is deceleration, the motor speed is not 0, the axle speed is not 0, and the throttle information is no throttle signal; The fourth strategy includes the motor torque being -1 N.m, and the input time being maintained until the motor speed is equal to the axle speed.

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