Motor torque increasing method
By setting the start time of torque addition during the motor shift process to the time period when the sprung mass moves away from the unsprung mass, and adjusting the vibration period based on load information, the torque addition strategy is optimized, which solves the gear shift jitter problem of electric commercial vehicles and achieves a balance between the vehicle's power and comfort.
Patent Information
- Application Number
- CN202410476347.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-04-19
- Publication Date
- 2025-10-24
AI Technical Summary
Electric commercial vehicles experience vehicle jitter due to sudden changes in motor torque during gear shifting. Existing technology reduces torque shock by extending the torque change time, but this results in longer gear shifting times and sacrifices vehicle power.
By setting the start time of motor torque application to the time period when the vehicle's sprung mass moves away from the unsprung mass, and ensuring that the torque application period is entirely in this direction, the vibration period is adjusted in combination with load information, and the torque application strategy is optimized to reduce vibration while maintaining vehicle dynamics.
It effectively suppresses motor shifting vibration, improves the comfort and power of the entire vehicle, and meets the needs of fast shifting.
Smart Images
Figure CN120830728A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of motor control, and particularly relates to a motor torque adding method capable of effectively inhibiting motor gear shifting jitter. BACKGROUND
[0002] With the increasingly clear electric trend of automobiles, more and more electric commercial vehicles appear in the market. AMT reduction boxes are widely used in automatic transmission electric commercial vehicles due to economy, and automatic shifting is realized through cooperation with motors. Since the motor has large starting torque and fast response, the torque impact on the vehicle is large. When the AMT gearbox is in the shifting process, the motor has conditions such as sudden increase and sudden decrease of torque to realize rapid shifting, which easily causes the vehicle cab to jitter during shifting.
[0003] At present, the conventional solution to the shifting jitter problem of automatic transmission electric vehicles is to prolong the motor torque change time and reduce the torque impact to alleviate the cab jitter caused by automatic shifting. However, this approach will cause a long shifting time, sacrificing the vehicle power performance. SUMMARY
[0004] The purpose of the application is to provide a motor torque adding method capable of effectively inhibiting motor gear shifting jitter and maintaining good vehicle power performance.
[0005] In order to achieve the above purpose, the motor torque adding method of the application is applied to vehicle motor gear shifting, and includes the following steps:
[0006] When the vehicle starts, the clear torque duration t1 of the vehicle motor, the gear shifting-timing-shifting duration t3, and the torque adding duration t2 are obtained.
[0007] The torque adding start time is set as the starting time of the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle in the nearest vibration period T, and the torque adding time period is completely in the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle.
[0008] The vehicle load signal is obtained when the vehicle starts, and when the load change amount exceeds the set threshold, the new vibration period T1 is recalculated and obtained. When the load does not change during vehicle driving, the original torque adding strategy is maintained.
[0009] The new sprung mass is obtained according to the load information, and the natural frequency f and the vibration period T1 are calculated according to the following formula:
[0010]
[0011]
[0012] Wherein, m1 is a new sprung mass, m2 is an unsprung mass, and k is a spring stiffness coefficient.
[0013] The vibration period T includes four time periods:
[0014] The first time period 0-T / 4: the sprung mass moves from the origin position to the far position away from the unsprung mass;
[0015] The second time period T / 4-T / 2: the sprung mass moves from the far position to the origin position close to the unsprung mass;
[0016] The third time period T / 2-3T / 4: the sprung mass moves from the origin position to the near position close to the unsprung mass;
[0017] The fourth time period 3T / 4-T: the sprung mass moves from the near position to the origin position away from the unsprung mass;
[0018] The time periods in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle are the first time period and the fourth time period.
[0019] In an embodiment of the motor twisting method, t1≤T / 4 and t2≤T / 4 are set.
[0020] In an embodiment of the motor twisting method, when t1+t3<3T / 4, the twisting start time is the time elapsed by 3T / 4 from the vibration start time.
[0021] In an embodiment of the motor twisting method, when 3T / 4≤t1+t3≤5T / 4-t2, the twisting start time is the time elapsed by t1+t3 from the vibration start time.
[0022] In an embodiment of the motor twisting method, when 5T / 4-t2<t1+t3<7T / 4, the twisting start time is the time elapsed by 7T / 4 from the vibration start time.
[0023] In an embodiment of the motor twisting method, when t1+t3≥7T / 4, the twisting start time is the time elapsed by t1+t3 from the vibration start time.
[0024] The motor twisting method of the present application has the beneficial effect that, by setting the twisting start time to be the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle in the nearest vibration period, and by making the twisting time completely in the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle, not only can the shaking caused by the whole vehicle resonance be reduced, but also the better power performance of the whole vehicle can be ensured.
[0025] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments, but not as a limitation to the present application. BRIEF DESCRIPTION OF DRAWINGS
[0026] Figure 1 A step diagram of an embodiment of the motor torsion adding method of the present application;
[0027] Figure 2 A schematic diagram of a simplified two-mass vibration system;
[0028] Figure 3 A force-motion diagram of the vibration system in the torsion clearing stage;
[0029] Figure 4 A motion diagram of the vibration system in one period T;
[0030] Figure 5 A force-motion diagram of the vibration system in the torsion adding stage;
[0031] Figure 6 A step diagram of an embodiment of the motor torsion adding method of the present application. DETAILED DESCRIPTION
[0032] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings and specific embodiments, so as to further understand the purposes, solutions and effects of the present application, but not as a limitation to the protection scope of the appended claims of the present application.
[0033] The motor torsion adding method of the present application is applied to vehicle motor gear shifting, such as Figure 1 as shown, comprising the following steps:
[0034] When the vehicle is started, the load signal is read, and it is determined whether the load changes. If not, the original strategy is maintained. If yes, the torsion clearing time t1, the time t3 of gear disengagement-speed adjustment-gear engagement, and the torsion adding time t2 of the vehicle motor are read, and the vibration period T is calculated.
[0035] The torsion adding start time is set as the time period in the latest vibration period T during which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle.
[0036] The present application changes the conventional means of reducing torque impact by prolonging the torque changing time in the prior art. The torsion adding start time is set as the time period in the latest vibration period T during which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle, and the torsion adding time period is completely in the time period during which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle. This not only reduces the shaking problem caused by vehicle resonance, but also ensures good vehicle power.
[0037] In detail, the vehicle can be simply divided into two parts: sprung mass and unsprung mass, connected by a leaf spring. For the convenience of analyzing the problem, Figure 2 As shown, it is simplified into a two-mass vibration system. Since the shifting process primarily involves changes in push and pull forces on the vehicle in the forward direction, it is treated as two masses subject to these forces, where m1 is the sprung mass, m2 is the unsprung mass, k is the leaf spring's elastic modulus, and c is the damping coefficient. For example, sprung mass m1 refers to the combined mass of all vehicle components supported by the suspension, including the body and engine, while unsprung mass m2 refers to the combined mass of all components supporting the suspension and its loads, including the wheels, tires, and a portion of the drive shaft.
[0038] The vibration system has a natural frequency f, as shown in formula (1), and the vibration period T of the vibration system is calculated according to formula (2).
[0039]
[0040]
[0041] When the sprung mass m1 increases, such as when the vehicle is loaded, the natural frequency f decreases and the vibration period T increases.
[0042] The vehicle shifting process can be divided into three stages:
[0043] 1. Torque Clearance Phase. The motor torque must be cleared before the transmission shifts. The duration of the torque clearance phase during the shifting process is set to t1.
[0044] 2. Shifting, motor speed regulation, and shifting phase: The shifting-shifting-speed regulation-shifting duration during the shifting process is set to t3.
[0045] 3. Torque Addition Phase: After the gear is engaged, the motor resumes outputting torque. The duration of the torque addition phase during the gear shift is set to t2.
[0046] During normal acceleration, the driving force, resistance, spring internal force, and inertia force are in balance, so the net force can be considered to be 0. During the torque removal and torque addition stages, the vehicle has torque changes, which will cause changes in push and pull forces. During the torque removal stage, the motor driving force is reset to zero within the torque removal time t1. The average force reduced during the torque removal time t1 can be set as F1. Figure 3 As shown, it is equivalent to applying an impact force with an average amplitude of F1 and a duration of t1 to the originally balanced vibration system. This force will cause the sprung mass m1 to move away from the unsprung mass m2.
[0047] Then, the system will produce a period of T = 1 / f attenuation vibration, generally will last several cycles, at this time for the whole vehicle, the cab belongs to the spring mass m1, and the position is higher, the driver can clearly feel the shaking.
[0048] One vibration cycle T movement as shown in Figure 4 , including four time periods.
[0049] Initial T0 = 0 moment, the vibration system is in the equilibrium position, the spring mass m1 relative to the spring mass m2 at the origin position.
[0050] After applying the impact force F1, in the first time period of T0 ~ T / 4, the spring mass m1 moves from the equilibrium position to the far position away from the spring mass m2. For example, in the direction shown, the spring mass m1 moves to the left, away from the spring mass m2. At this time, the spring mass m1 bears the tension of the spring.
[0051] In the second time period of T / 4 ~ T / 2, the spring mass m1 moves from the far position to the equilibrium position close to the spring mass m2. For example, in the direction shown, the spring mass m1 moves to the right, close to the spring mass m2. At this time, the spring mass m1 bears the tension of the spring.
[0052] In the third time period of T / 2 ~ 3T / 4, the spring mass m1 moves from the equilibrium position to the near position close to the spring mass m2. For example, in the direction shown, the spring mass m1 moves to the right, close to the spring mass m2. At this time, the spring mass m1 bears the thrust of the spring.
[0053] In the fourth time period of 3T / 4 ~ T, the spring mass m1 moves from the near position to the equilibrium position away from the spring mass m2. For example, in the direction shown, the spring mass m1 moves to the left, away from the spring mass m2, at this time the spring mass m1 bears the thrust of the spring.
[0054] Among them, the vibration generally lasts several cycles, and the start and end time of the four time periods of the nth cycle needs to be added (n-1)T, n = 1, 2, 3 … For example, the start and end time of the third time period of the second cycle is 3T / 2 ~ 7T / 4.
[0055] In the twisting stage, as Figure 5 , the motor driving force increases to the allowable value within the time t2, which is equivalent to applying an impact force with an average amplitude of F2 and an action time of t2 to the vibration system, which will make the spring mass m1 close to the spring mass m2.
[0056] If the action time of F2 is in the second time period of T / 4-T / 2 and the third time period of T / 2-3T / 4 of the vibration period T, the direction of the force F2 is the same as the moving direction of the spring mass m1, obviously, the kinetic energy of the spring mass m1 is increased, and then the vibration amplitude of the vibration system is amplified. If the action time of F2 is in the first time period of T0-T / 4 and the fourth time period of 3T / 4-T of the vibration period T, the direction of the force F2 is opposite to the moving direction of the spring mass m1, then the kinetic energy of the spring mass m1 is decreased, and the vibration amplitude of the vibration system is reduced.
[0057] The present application sets the starting time of the torsion as the time period of the spring mass of the vehicle moving away from the unsprung mass of the vehicle in the latest vibration period T, and makes the torsion time completely in the time period of the spring mass of the vehicle moving away from the unsprung mass of the vehicle, that is, the present application sets the starting time of the torsion, and makes the torsion time in the first time period or the fourth time period of the latest vibration period T, so that the vehicle has both the comfort and the whole vehicle dynamic performance.
[0058] For example, the torsion stage is completely in the first time period of the latest vibration period T, the fourth time period of the latest vibration period T, or the fourth time period of the latest vibration period T and the first time period of the next vibration period T, which can achieve the effect that the direction of the force F2 of the torsion stage is opposite to the moving direction of the spring mass m1, the kinetic energy of the spring mass m1 is decreased, and the vibration amplitude of the vibration system is reduced.
[0059] The present application sets the appropriate torsion time according to the vibration characteristics of the system, eliminates the resonance, and meets the shift dynamic performance and the smoothness of the whole vehicle.
[0060] In the formula (1), the elastic stiffness coefficient k and the unsprung mass m2 of the vibration system are built in; the new spring mass m1 is obtained according to the load information, and the natural frequency f and the vibration period T are calculated according to the above formula (1) and formula (2).
[0061] In an embodiment of the present application, the vehicle load signal is obtained when the whole vehicle starts, and the new vibration period T is recalculated and obtained when the load change amount exceeds the set threshold. If the load change amount is within the threshold, the original torsion strategy can be maintained. That is, the starting time of the torsion is placed in the first time period and the fourth time period of the latest vibration period T, and preferably, the whole torsion stage is in the first time period and the fourth time period of the latest vibration period T.
[0062] When the load change amount of the vehicle exceeds the threshold, the starting time of the torsion needs to be reset according to the obtained new vibration period T, so that the torsion time is completely in the time period of the spring mass m1 moving away from the unsprung mass m2, the resonance is eliminated, and the comfort is improved.
[0063] The cleaning torsion duration t1, the shifting - speed - adjusting - shifting duration t3, and the torsion - adding duration t2 are all fixed values. Since the mass above the spring (i.e., the load) of the vibration system often changes, the vibration period T is actually a variable value. The motor's torsion - adding time can only reduce the jitter amplitude of the vibration system when it acts on the period during which the mass m1 above the spring moves away from the mass m2 below the spring. The core of this invention is to adjust the starting moment of torsion - adding according to the vibration period T.
[0064] As Figure 6 shown, in the following process, t1 + t3 is the duration of the two stages before shifting (the cleaning - torsion stage and the stage of motor speed - adjusting and shifting after gear - disengaging). The end moment of t1 + t3 is also the earliest starting moment when torsion - adding can be carried out, which is used to judge whether the torsion - adding time is in the period during which the mass m1 above the spring moves away from the mass m2 below the spring. If so, torsion - adding can start at the end moment of t1 + t3; otherwise, it is postponed to the starting moment of the period during which the mass m1 above the spring moves away from the mass m2 below the spring.
[0065] For the whole vehicle to shift gears quickly, both cleaning torsion and torsion - adding are required to be rapid. Usually, both t1 and t2 are less than T / 4. And because gear - disengaging, speed - adjusting, and gear - engaging take time, the torsion - adding time cannot appear in the first time period of T0 - T / 4 of the first vibration period T. Therefore, the shifting - torsion - adding strategy is formulated as follows:
[0066] Obtain the mass m1 above the spring according to the vehicle load signal, judge whether the load change amount is greater than the threshold value. Otherwise, maintain the original torsion - adding moment. If so, calculate the new vibration period T, and set the torsion - adding moment according to the following strategy.
[0067] If t1 + t3 < 3T / 4, start torsion - adding at the moment of 3T / 4 after the start of vibration;
[0068] If 3T / 4 ≤ t1 + t3 ≤ 5T / 4 - t2, start torsion - adding at the moment of t1 + t3 after the start of vibration;
[0069] If 5T / 4 - t2 < t1 + t3 < 7T / 4, start torsion - adding at the moment of 7T / 4 after the start of vibration;
[0070] If t1 + t3 ≥ 7T / 4, start torsion - adding at the moment of t1 + t3 after the start of vibration.
[0071] Under normal circumstances, shifting gears can be completed within two vibration periods T. Therefore, the above - mentioned several situations can cover the shifting use requirements of the whole vehicle from no - load to full - load.
[0072] For example, the inherent frequency f of a heavy truck is 1.25 Hz, the vibration period T is 0.8 s, the untwisting time t1 is 0.13 s, the twisting time t2 is 0.18 s, the gear shifting-motor speed adjusting-gear engaging time t3 is 1 s. Since 5T / 4-t2 < t1+t3 < 7T / 4, the starting time of the twisting stage is set as 1.4 s of 7T / 4.
[0073] The inherent frequency f of a heavy truck is 0.833 Hz, the vibration period T is 1.2 s, the untwisting time t1 is 0.13 s, the twisting time t2 is 0.18 s, the gear shifting-motor speed adjusting-gear engaging time t3 is 1 s. Since 3T / 4 ≤ t1+t3 ≤ 5T / 4-t2, the starting time of the twisting stage is set as 1.13 s of t1+t3.
[0074] The inherent frequency f of a heavy truck is 1.54 Hz, the vibration period T is 0.65 s, the untwisting time t1 is 0.13 s, the twisting time t2 is 0.18 s, the gear shifting-motor speed adjusting-gear engaging time t3 is 1 s. Since t1+t3 ≥ 7T / 4, the starting time of the twisting stage is set as 1.13 s of t1+t3.
[0075] Since the change of the load only occurs when the vehicle is stopped, in order to save the calculation resource, the strategy is only triggered when the vehicle starts, i.e. the above-mentioned twisting control strategy is executed in the vehicle starting stage.
[0076] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims attached to the present application.
Claims
1. A method for motor torqueing, applied to vehicle motor gear shifting, characterized in that, The method comprises the following steps: The vehicle is started, and the torsion duration t1 of the motor of the vehicle, the duration t3 of gear shifting-speed regulation-gear engagement, and the torsion duration t2 are obtained; The start time of the torsion is set as the start time of the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle, and the torsion time period is completely in the time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle.
2. The motor twisting method of claim 1, wherein, The vehicle load signal is obtained when the vehicle is started, and the new vibration period T1 is recalculated and obtained when the load change amount exceeds the set threshold.
3. The motor torsion method according to claim 1, characterized in that, The new sprung mass is obtained according to the load information, and the new natural frequency f and the new vibration period T1 are calculated according to the following formula: Wherein, m1 is the new sprung mass, m2 is the unsprung mass, and k is the elastic stiffness coefficient of the leaf spring.
4. The motor twisting method of claim 1, wherein, The vibration period T comprises four time periods: The first time period 0-T / 4: the sprung mass moves from the original position to the far position away from the unsprung mass; The second time period T / 4-T / 2: the sprung mass moves from the far position to the original position close to the unsprung mass; The third time period T / 2-3T / 4: the sprung mass moves from the original position to the near position close to the unsprung mass; The fourth time period 3T / 4-T: the sprung mass moves from the near position to the original position away from the unsprung mass; The time period in which the sprung mass of the vehicle moves away from the unsprung mass of the vehicle is the first time period and the fourth time period.
5. The motor twisting method of claim 1, wherein, The original torsion strategy is maintained when the load does not change during the vehicle driving process.
6. The motor twisting method according to any one of claims 1 to 4, characterized by, t1≤T / 4 and t2≤T / 4 are set.
7. The motor twisting method of claim 6, wherein, When t1+t3<3T / 4, the start time of the torsion is the time when the vibration starts after 3T / 4.
8. The motor twisting method of claim 6, wherein, When 3T / 4≤t1+t3≤5T / 4-t2, the start time of the torsion is the time when the vibration starts after t1+t3.
9. The motor twisting method of claim 6, wherein, When 5T / 4-t2<t1+t3<7T / 4, the start time of the torsion is the time when the vibration starts after 7T / 4.
10. The motor twisting method of claim 6, wherein, When t1+t3≥7T / 4, the start time of the torsion is the time when the vibration starts after t1+t3.