Pure electric vehicle gearbox and control method thereof

Abstract

The invention discloses a pure electric vehicle gearbox. The gearbox comprises a motor; the double clutch is connected with the output end of the motor; the input shaft comprises a second-gear input shaft, and one end of the second-gear input shaft is connected with the double clutch; one end of the first-gear input shaft is connected with the double clutch, and the second-gear input shaft is sleeved with the first-gear input shaft in an empty mode; the first-gear driving gear is fixedly arranged at the other end of the first-gear input shaft in a sleeving manner; the second-gear driving gear is fixedly arranged at the other end of the second-gear input shaft in a sleeving manner; the driving shaft is parallel to the input shaft; the first-gear driven gear is fixedly arranged on the driving shaft in a sleeving manner and is meshed with the first-gear driving gear; the second-gear driven gear is fixedly arranged on the driving shaft in a sleeving manner and is meshed with the second-gear driving gear; two ends of the half shaft are connected with the wheels; and the differential mechanism is fixedly arranged on the half shaft in a sleeving manner and is connected with the driving shaft through a reduction gear. The invention further provides a control method of the pure electric vehicle gearbox.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pure electric vehicle transmission system control, and particularly relates to a pure electric vehicle gearbox and a control method thereof. BACKGROUND

[0002] With the development of the new energy automobile industry, pure electric vehicles have become an important development direction due to energy saving and zero pollution. At present, pure electric vehicles mostly adopt the configuration of motor direct drive plus single-stage reducer, and although multi-gear transmission can improve power performance and endurance, it is not widely used due to problems such as great control difficulty and high cost. The double-clutch transmission (DCT) has become an optimal solution for the multi-gear of pure electric vehicles due to its simple structure, high transmission efficiency and no power interruption during gear shifting.

[0003] In the existing gear shifting control strategy, the PID control is widely used due to its simple algorithm, but when facing the model parameter uncertainty (such as friction factor change and rotational inertia error) and unknown disturbance (such as road fluctuation and load mutation) in the gear shifting process, its robustness is insufficient, which easily leads to the increase of gear shifting impact and sliding friction work, and affects the driving comfort and clutch life. Therefore, there is an urgent need for a gear shifting control method that can effectively suppress disturbance and improve control accuracy. SUMMARY

[0004] The application aims to provide a pure electric vehicle gearbox, which has a simple structure, is convenient to control, and can improve the gear shifting efficiency.

[0005] The application also aims to provide a control method of the pure electric vehicle gearbox, which can enhance the system robustness, reduce the impact and sliding friction work.

[0006] The application provides the following technical solutions:

[0007] A pure electric vehicle gearbox comprises:

[0008] a motor;

[0009] a double clutch connected with the output end of the motor;

[0010] an input shaft comprising:

[0011] a two-gear input shaft, one end of which is connected with the double clutch;

[0012] a one-gear input shaft, one end of which is connected with the double clutch and is sleeved on the two-gear input shaft;

[0013] a one-gear driving gear, which is fixedly sleeved on the other end of the one-gear input shaft;

[0014] a two-gear driving gear, which is fixedly sleeved on the other end of the two-gear input shaft;

[0015] a drive shaft, which is parallel to the input shaft;

[0016] a first-gear driven gear, which is fixedly sleeved on the drive shaft and engaged with the first-gear driving gear;

[0017] a second-gear driven gear, which is fixedly sleeved on the drive shaft and engaged with the second-gear driving gear;

[0018] half shafts, the two ends of which are connected with wheels;

[0019] differential gears, which are fixedly sleeved on the half shafts and connected with the drive shaft through reduction gears.

[0020] Preferably, the double clutch comprises:

[0021] a first-gear clutch, which comprises:

[0022] a first-gear driving part, which is connected with the output end of the motor;

[0023] a first-gear driven part, which is fixedly connected with the first-gear driving gear through the first-gear input shaft;

[0024] a second-gear clutch, which comprises:

[0025] a second-gear driving part, which is connected with the output end of the motor;

[0026] a second-gear driven part, which is fixedly connected with the second-gear driving gear through the second-gear input shaft.

[0027] Preferably, the reduction gears comprise:

[0028] a main reduction gear, which is fixedly sleeved on the drive shaft;

[0029] a slave reduction gear, which is loosely sleeved on the half shaft and engaged with the main reduction gear; the slave reduction gear is fixedly connected with the differential gear.

[0030] Preferably, it further comprises:

[0031] a motor sensor, which is arranged on the motor and used for detecting the running state of the motor;

[0032] a gearbox control unit, which is used for controlling the combination and separation of the double clutch; the gearbox control unit further comprises an anti-interference controller, which outputs a control signal to control the output torque and the rotational angular velocity of the motor.

[0033] A control method of a gearbox of a pure electric vehicle, comprising:

[0034] When the gearbox is in one gear, the one-gear clutch is engaged, the two-gear clutch is disengaged, and the double clutch is in one-gear engagement state; power is transmitted from the motor to the one-gear driving gear through the one-gear clutch of the double clutch, and then to the half shaft through the one-gear driven gear, the drive shaft, the reduction gear and the differential, to drive the wheels to run;

[0035] When the gearbox is in two gears, the two-gear clutch is engaged, the one-gear clutch is disengaged, and the double clutch is in two-gear engagement state; power is transmitted from the motor to the two-gear driving gear through the two-gear clutch of the double clutch, and then to the half shaft through the two-gear driven gear, the drive shaft, the reduction gear and the differential, to drive the wheels to run;

[0036] The shifting process includes:

[0037] The preparation stage is a stage in which the one-gear clutch alone transmits motor torque, and the two-gear clutch does not transmit motor torque;

[0038] The torque stage is a stage in which the one-gear clutch is gradually disengaged, the two-gear clutch is gradually engaged, and the one-gear power transmission route is switched to the two-gear power transmission route;

[0039] The inertia stage is a stage in which the one-gear clutch does not transmit motor torque, the motor is adjusted to reduce the speed difference between the two-gear driving part and the two-gear driven part of the two-gear clutch to a two-gear set threshold value, and the two-gear clutch is completely engaged.

[0040] Preferably, it further includes:

[0041] The preparation stage is that after the gearbox control unit detects the vehicle upshift signal, the oil pressure of the one-gear clutch is rapidly reduced to the sliding friction value, the one-gear clutch is released from the locked state but still maintains the sliding friction state to transmit power; the oil of the two-gear clutch is quickly filled to eliminate the air gap and reach the critical contact point, and the two-gear clutch reaches the state of being about to engage but not transmitting torque;

[0042] The torque stage is that the gearbox control unit controls the oil pressure of the one-gear clutch to continue to decrease to zero, controls the oil pressure of the two-gear clutch to gradually increase to the two-gear set threshold value, controls the torque of the motor to be adjusted from the one-gear initial value to the two-gear set threshold value, and completes the power transmission route switching;

[0043] In the inertia stage, the gearbox control unit controls the oil pressure of the first clutch to be zero, and the second clutch is in a slipping state; the disturbance controller adjusts the torque and angular velocity of the motor; when the speed difference between the second clutch driving part and the second clutch driven part is less than the second clutch set threshold, the oil pressure of the second clutch is quickly increased, the second clutch is fully engaged, and the gear shifting operation is completed.

[0044] Preferably, the control method of the disturbance controller is:

[0045] The actual motor rotation angular velocity and the motor output torque are obtained through the motor sensor;

[0046] The actual motor rotation angular velocity and the motor output torque are input into a linear extended state observer, and the linear extended state observer outputs a motor rotation angular velocity observation value and a disturbance estimation value;

[0047] The desired motor rotation angular velocity is obtained; the desired motor rotation angular velocity and the motor rotation angular velocity observation value are input into a feedback control module, and the feedback control module outputs a feedback control amount;

[0048] The feedback control amount and the disturbance estimation value are input into a control amount calculation module, and the control amount calculation module outputs a total control amount;

[0049] The total control amount is used to control the torque and the actual motor rotation angular velocity of the motor, and a closed-loop control is formed.

[0050] Preferably, the feedback control amount is:

[0051]

[0052] In the formula, u0 is the feedback control amount; K p is the proportional gain of the controller; ω d is the desired motor rotation angular velocity; is the motor rotation angular velocity observation value.

[0053] Preferably, the total control amount is:

[0054]

[0055] In the formula, u is the total control amount; z2 is the disturbance component of the observation value of the linear extended state observer; I' m is the inverse of the equivalent rotational inertia of the motor shaft.

[0056] The beneficial effects of the present application are:

[0057] The pure electric vehicle gearbox provided by the present application has simple structure, convenient control, and can improve the gear shifting efficiency.

[0058] The control method of the pure electric vehicle gearbox provided by the application can enhance system robustness, reduce impact degree and sliding friction work, improve driving comfort, and prolong clutch service life. BRIEF DESCRIPTION OF DRAWINGS

[0059] Figure 1 The structure diagram of the pure electric vehicle gearbox according to the application.

[0060] Figure 2 The clutch angular velocity diagram of the upshift process of the pure electric vehicle gearbox according to the application.

[0061] Figure 3 The clutch torque diagram of the upshift process of the pure electric vehicle gearbox according to the application.

[0062] Figure 4 The structure diagram of the disturbance rejection controller according to the application.

[0063] Figure 5 The disturbance rejection controller and the PID controller without interference angular velocity tracking comparison diagram according to the application.

[0064] Figure 6 The disturbance rejection controller and the PID controller without interference angular velocity tracking error comparison diagram according to the application.

[0065] Figure 7 The disturbance rejection controller and the PID controller with interference angular velocity tracking comparison diagram according to the application.

[0066] Figure 8 The disturbance rejection controller and the PID controller with interference angular velocity tracking error comparison diagram according to the application.

[0067] Figure 9 The angular velocity change diagram of the motor and the clutch in the upshift process of the disturbance rejection controller under the interference condition according to the application.

[0068] Figure 10 The torque change diagram of the motor and the clutch in the upshift process of the disturbance rejection controller under the interference condition according to the application.

[0069] Figure 11 The upshift impact degree diagram according to the application.

[0070] Figure 12 The upshift sliding friction work diagram according to the application.

[0071] Figure numerals: motor 110, first gear clutch 121, second gear clutch 122, first gear driving gear 211, first gear driven gear 212, first gear input shaft 213, second gear driving gear 221, second gear driven gear 222, second gear input shaft 223, drive shaft 230, half shaft 310, main reduction gear 321, slave reduction gear 322, differential 330, wheel 340. DETAILED DESCRIPTION

[0072] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0073] like Figure 1 As shown, the present invention provides a pure electric vehicle transmission, comprising: a motor 110; a dual clutch for transmitting the motor output torque to the transmission; the dual clutch comprising: a first-gear clutch 121 comprising: a first-gear active portion connected to the output end of the motor 110; a first-gear driven portion; and a second-gear clutch 122 comprising: a second-gear active portion connected to the output end of the motor 110; and a second-gear driven portion.

[0074] The transmission includes: an input shaft, which includes: a second-gear input shaft 223, one end of which is connected to the dual clutch; a first-gear input shaft 213, one end of which is connected to the dual clutch and is loosely sleeved on the second-gear input shaft 223; a first-gear driving gear 211, which is fixedly sleeved on the other end of the first-gear input shaft 213 and fixedly connected to the first-gear driven part through the first-gear input shaft 213; a second-gear driving gear 221, which is fixedly sleeved on the other end of the second-gear input shaft 223 and fixedly connected to the second-gear driven part through the second-gear input shaft 223; a drive shaft 230, which is arranged parallel to the input shaft; a first-gear driven gear 212, which is fixedly sleeved on the drive shaft 230 and meshed with the first-gear driving gear 211; and a second-gear driven gear 222, which is fixedly sleeved on the drive shaft 230 and meshed with the second-gear driving gear 221.

[0075] The half shaft 310 is connected to the wheels 340 at both ends. The reduction gears include: a main reduction gear 321, which is fixedly mounted on the drive shaft 230; a secondary reduction gear 322, which is loosely mounted on the half shaft 310 and meshes with the main reduction gear 321; and a differential 330, which is fixedly mounted on the half shaft 310 and fixedly connected to the secondary reduction gear 322. The differential 330 is connected to the drive shaft 230 via the reduction gears.

[0076] A motor sensor is arranged on the motor 110 to detect the operating state of the motor 110; a gearbox control unit controls the engagement and disengagement of the double clutch by controlling the hydraulic system proportional solenoid valve of the clutch; the gearbox control unit further comprises an anti-disturbance controller which outputs a control signal to control the output torque and rotational angular velocity of the motor.

[0077] The power transmission route of the pure electric vehicle gearbox is as follows:

[0078] When the gearbox is in one gear, the one-gear clutch 121 is engaged, the two-gear clutch 122 is disengaged, and the double clutch is in one-gear engagement state; power is transmitted from the motor 110 to the one-gear driving gear 211 through the one-gear clutch 121 of the double clutch, and then transmitted to the half shaft 310 through the one-gear driven gear 212, the drive shaft 230, the reduction gear and the differential 330, to drive the wheels 340 to run.

[0079] When the gearbox is in two gears, the two-gear clutch 122 is engaged, the one-gear clutch 121 is disengaged, and the double clutch is in two-gear engagement state; power is transmitted from the motor 110 to the two-gear driving gear 221 through the two-gear clutch 122 of the double clutch, and then transmitted to the half shaft 310 through the two-gear driven gear 222, the drive shaft 230, the reduction gear and the differential 330, to drive the wheels 340 to run.

[0080] The mechanical model is established according to the structure of the pure electric vehicle gearbox as follows:

[0081] The motor output torque is:

[0082] T m = f (α, n m )

[0083] In the formula, T m is the motor output torque; α is the pedal opening; n m is the motor speed.

[0084] The output shaft of the motor 110 is rigidly connected with the driving shaft of the clutch, and the power balance equation is:

[0085]

[0086] In the formula, I m is the equivalent rotational inertia of the motor output shaft; is the motor rotational angular acceleration; b m is the rotational damping factor of the motor output shaft; ω m is the motor rotational angular velocity, which is also the angular velocity of the clutch driving disc; T LT1 is the friction torque of the one clutch; T2 is the friction torque of the two clutch. H T2 is the friction torque of the two clutch.

[0087] The motor output torque is transmitted through the double clutch, and the clutch transmission torque is:

[0088]

[0089] Wherein,

[0090] In the formula, T c T is the clutch transmission torque; sgn is the sign function; Δω mc is the angular velocity difference between the clutch driving disc and the driven disc; μ d is the clutch dynamic friction factor; R is the effective radius of the clutch; F1 is the force acting on the clutch; ω c is the angular velocity of the clutch driven disc; T s is the static friction torque.

[0091] During the shifting process, the transmission torque phase model is:

[0092]

[0093] In the formula, I L is the moment of inertia of the one input shaft; is the angular acceleration of the one input shaft; b L is the rotational damping factor of the one input shaft; ω L is the angular velocity of the one input shaft; T1 is the load torque of the one input shaft; I H is the moment of inertia of the two input shaft; is the angular acceleration of the two input shaft; b H is the rotational damping factor of the two input shaft; ω H is the angular velocity of the two input shaft; T2 is the load torque of the two input shaft; T0 is the half shaft input torque; c0 is the main transmission ratio; c1 is the one transmission ratio; c2 is the two transmission ratio.

[0094] The torque phase model of the pure electric vehicle transmission is:

[0095]

[0096] The output torque of the pure electric vehicle transmission is transmitted to the wheel model by the drive shaft:

[0097]

[0098] Wherein,

[0099] In the formula, I' wEquivalent rotational inertia of drive shaft Rotational angular acceleration of drive shaft w Rotational damping factor of drive shaft w Rotational angular velocity of drive shaft F2 is driving force of wheel; r is wheel radius; I0 is rotational inertia of differential; I w Rotational inertia of half shaft f Rotational inertia of wheel b0 is rotational damping factor of differential w Rotational damping factor of half shaft f Rotational damping factor of wheel

[0100] Driving force of wheel is:

[0101]

[0102] In the formula, G is gravity of automobile; η f Rolling resistance coefficient of tire; β is road slope; γ k Air resistance coefficient; S is windward area; v is vehicle speed; δ is rotational mass conversion coefficient of automobile; m is mass of automobile.

[0103] Oil pressure of hydraulic actuator in clutch and proportional pressure solenoid valve current are related as:

[0104]

[0105] In the formula, p ev Oil pressure of hydraulic actuator in clutch; τ ev Time coefficient; K ev Pressure gain coefficient; i is proportional solenoid valve current.

[0106] As Figures 2-3 shown, in order to ensure smoothness and robustness of gear shifting, taking upshift process as an example, gear shifting process is set to include: preparation stage, torque stage and inertia stage.

[0107] Preparation stage is a stage in which the first clutch 121 alone transmits motor torque and the second clutch 122 does not transmit motor torque; in the gear shifting process, after the transmission control unit detects a vehicle upshift signal, the oil pressure of the first clutch 121 is rapidly reduced to a sliding friction value by controlling the proportional pressure solenoid valve of the hydraulic system, the first clutch 121 is released from the locked state but still maintains the sliding friction state to transmit power; the second clutch 122 is quickly filled with oil to eliminate the idle stroke and reach the critical contact point, and the second clutch 122 reaches a state of being about to be combined but not transmitting torque.

[0108] Torque phase, which is a phase that the first clutch 121 is gradually separated, the second clutch 122 is gradually combined, the first power transmission route is switched to the second power transmission route; the clearance elimination phase, the gearbox control unit controls the oil pressure of the first clutch 121 to continuously decrease to zero, controls the oil pressure of the second clutch 122 to gradually increase to the second gear set threshold value, controls the torque of the motor 110 to adjust from the first gear initial value to the second gear set threshold value, and completes the power transmission route switching. In the torque phase, if the first clutch 121 is separated too fast or the second clutch 122 is combined too slowly, the transmitted torque will be interrupted, so the driving disc rotation speed of the second clutch 122 is greater than or equal to the driven disc rotation speed.

[0109] The relationship between the motor torque and the first clutch torque and the second clutch torque in the torque phase is:

[0110]

[0111] Wherein,

[0112] In the formula, I' is the converted first input shaft rotational inertia; b' is the converted first input shaft rotation damping factor; T is the comprehensive torque. L L 12

[0113] Inertia phase, which is a phase that the first clutch 121 does not transmit the motor torque, the motor 110 is adjusted to reduce the speed difference between the second driving part and the second driven part of the second clutch 122 to the second gear set threshold value, and the second clutch 122 is completely combined. The inertia phase designs a disturbance controller to control the output torque and angular velocity of the motor 110, which can enhance the system robustness, reduce the impact and sliding friction work, improve the driving comfort, and prolong the service life of the clutch. The gearbox control unit controls the oil pressure of the first clutch 121 to decrease to zero, and the second clutch 122 is in a sliding state; the disturbance controller adjusts the torque and angular velocity of the motor 110; when the speed difference between the second driving part and the second driven part of the second clutch 122 is less than the second gear set threshold value, the oil pressure of the second clutch 122 is quickly increased, the second clutch 122 is completely combined, and the gear shifting operation is completed.

[0114] The unmodeled parts of the motor and the clutch, the model parameter errors and unknown disturbances are designed as uncertain terms d(t), and the power balance equation of the output shaft of the motor 110 and the driving shaft of the clutch can be obtained as follows:

[0115]

[0116] ​​​Where d(t) is the uncertainty term, including the unmodeled parts of the motor and clutch, model parameter errors, and unknown disturbances.

[0117] like Figure 4 As shown, according to the structure of the disturbance rejection controller, the state space equation can be obtained as follows:

[0118]

[0119] in,

[0120] Where x1 and x2 are state variables; is the derivative of the state variable x1; is the derivative of the state variable x2; y is the output; I′ m is the inverse of the equivalent moment of inertia of the motor shaft; u is the total control quantity; f0 is the interference related function; is the derivative of f0; h(t) is the interference correlation function; is the observed value of the motor rotation angular velocity; t is the time;

[0121] The state space equation of the linear extended state observer is:

[0122]

[0123] in,

[0124] Where z is the observation value of the linear extended state observer; is the rate of change of the observation value of the linear extended state observer; z1 is the angular velocity component of the observation value of the linear extended state observer; A is the interference coefficient matrix; B is the control quantity coefficient matrix; L is the feedback gain matrix of the linear extended state observer, l1 and l2 are constants; is the output observation value;

[0125]

[0126] in,

[0127] Where z2 is the interference component of the observation value of the linear extended state observer; is the observed value of f0; is the interference observation value The derivative of

[0128] The characteristic polynomial is:

[0129] λ(s)=s 2 +l1s+l2=(s+ε) 2

[0130] Gains l1 = 2ω0 and l2 = ω0 2 Select by characteristic polynomial;

[0131] Where λ(s) is the characteristic polynomial, s is the polynomial variable, and ε is the bandwidth of the linear extended state observer.

[0132] The linear extended state observer can observe external and internal disturbances in real time, and we can obtain:

[0133]

[0134] The calculation equation of the feedback control module is:

[0135]

[0136] Where, u0 is the feedback control quantity; K p is the proportional gain of the controller; ω d is the desired angular velocity of the motor;

[0137] The linear extended state observer can observe the disturbance in real time and compensate for the disturbance, and we can get:

[0138]

[0139] The control method of the anti-disturbance controller is as follows: obtaining the actual rotational angular velocity of the motor and the output torque of the motor through the motor sensor; inputting the actual rotational angular velocity of the motor and the output torque of the motor into a linear extended state observer, and the linear extended state observer outputs the motor rotational angular velocity observation value and the disturbance estimation value; obtaining the driver's intention according to the rotation of the steering wheel, thereby obtaining the expected rotational angular velocity of the motor; inputting the expected rotational angular velocity of the motor and the motor rotational angular velocity observation value into a feedback control module, and the feedback control module outputs a feedback control quantity; inputting the feedback control quantity and the disturbance estimation value into a control quantity calculation module, and the control quantity calculation module outputs a total control quantity; and using the total control quantity to control the torque and the actual rotational angular velocity of the motor to form a closed-loop control.

[0140] like Figures 5-12 As shown in Figure 2, simulation experiments are carried out on the anti-disturbance controller and the PID controller.

[0141] like Figures 5-6 As shown in the figure, when the model and parameters remain unchanged, different controllers are used to track the required angular velocity. When there is no interference, both the anti-disturbance controller and the PID controller can track the desired angular velocity, but the anti-disturbance controller has better tracking effect, with a maximum tracking error of 0.684 rad / s and a faster response. The maximum tracking error of the PID controller is 0.747 rad / s, and the error of the anti-disturbance controller is always smaller than that of the PID controller during the whole process.

[0142] As Figures 7-8 shown, in the case of unchanged model and parameters, the demand angular velocity is tracked by using different controllers, although there is disturbance, the anti-disturbance controller and the PID controller can still complete angular velocity tracking, but the anti-disturbance controller has smaller fluctuation, the control curve is smoother, and the load on the actuator is smaller, which proves that the disturbance can be observed and compensated in real time through the linear extended state observer, and the anti-disturbance controller has stronger anti-disturbance ability.

[0143] As Figures 9-10 shown, in the torque stage, the rotating speed of the motor 110 is higher than the rotating speed of the first clutch 121, and the reason can be that the motor output torque is greater than the clutch transmission torque; at the end of the inertia stage, due to the inertia torque, the rotating speed of the motor 110 is lower than the rotating speed of the second clutch 122. Since the transmission ratio of the first gear is greater than that of the second gear, in order to keep the acceleration of the vehicle from changing greatly, in the torque stage, the motor output torque needs to be increased; in the inertia stage, the rotating speed of the motor 110 is reduced by reducing the motor output torque, so that the rotating speed of the driving disc and the driven disc of the second clutch 122 is quickly synchronized. After the shift is completed, the motor output torque returns to the driver demand torque. During the shift process, the rotating speed of the motor and the clutch does not change suddenly, and smooth shifting is achieved.

[0144] As Figures 11-12 shown, the maximum shift impact degree is 8.67 m / s 3 , which meets the national recommended standard. The impact degree is the largest at the beginning of the torque stage and the end of the inertia stage, because the clutch transmission torque changes suddenly. The sliding friction work generated by the shift is 2646.76 J. The impact degree and the sliding friction work of the anti-disturbance controller are smaller than those of the PID controller; the anti-disturbance controller can improve the shift quality and is more suitable for real vehicle scenes with complex disturbance.

[0145] The pure electric vehicle gearbox provided by the application has simple structure, convenient control and improved shift efficiency; the combination structure of the double clutch and the first gear input shaft sleeved on the second gear input shaft is adopted, power is transmitted through the meshing of the independent first gear driving gear and driven gear and the second gear driving gear and driven gear, the rapid switching of the power transmission route is realized, and the shift efficiency is improved; at the same time, through the collaborative design of the reduction gear and the differential, the stable power output to the wheels is ensured, the overall structure is compact, and the transmission loss is low.

[0146] The control method of the pure electric vehicle gearbox provided by the application can enhance system robustness, reduce impact degree and sliding friction work, improve driving comfort, and prolong the service life of the clutch; the oil pressure state of the clutch is adjusted in advance in the preparation stage, the power transmission route is smoothly transitioned in the torque stage, the motor torque and angular velocity are accurately adjusted by the disturbance rejection controller in the inertia stage, the speed difference between the driving part and the driven part of the clutch is quickly converged to the set threshold, the gear shifting impact degree and the sliding friction work are significantly reduced, and the driving comfort is improved; the linear extended state observer is introduced to construct the disturbance rejection controller, the motor operating state can be monitored and the internal and external disturbances of the system can be estimated in real time, the disturbances are dynamically compensated through closed-loop control, the angular velocity tracking error is smaller and the fluctuation is more gentle when compared with the traditional PID control, the system robustness is enhanced, and the service life of the clutch is prolonged; the requirements of the pure electric vehicle for power performance and endurance capability are considered, the motor working interval is optimized through multi-gear adjustment, different driving conditions can be adapted to, and an effective solution is provided for improving the vehicle power performance and energy utilization efficiency.

[0147] Although the embodiments of the application have been disclosed as above, they are not limited to the application listed in the specification and the embodiments, and can be fully applied to various fields suitable for the application, and other modifications can be easily realized by those skilled in the art, therefore, the application is not limited to specific details and the figures shown and described herein, without departing from the general concept defined by the claims and the equivalent scope.

Claims

1. A pure electric vehicle gearbox, characterized in that: include: Motor; a dual clutch connected to an output end of the motor; An input shaft comprising: a second gear input shaft, one end of which is connected to the dual clutch; a first gear input shaft, one end of which is connected to the dual clutch and is loosely sleeved on the second gear input shaft; A first gear driving gear, which is fixedly sleeved on the other end of the first gear input shaft; A second gear driving gear, which is fixedly sleeved on the other end of the second gear input shaft; a drive shaft disposed parallel to the input shaft; a first-gear driven gear, which is fixedly sleeved on the drive shaft and meshes with the first-gear driving gear; A second-gear driven gear, which is fixedly sleeved on the drive shaft and meshes with the second-gear driving gear; Axle shafts, whose ends are connected to the wheels; The differential is fixedly sleeved on the half shaft and connected to the drive shaft through a reduction gear.

2. The pure electric vehicle gearbox according to claim 1, characterized in that: The dual clutch comprises: The first gear clutch comprises: A first-gear active part connected to the output end of the motor; a first gear driven part, which is fixedly connected to the first gear driving gear via the first gear input shaft; The second gear clutch comprises: A second-gear active part connected to the output end of the motor; The second gear driven part is fixedly connected to the second gear driving gear through the second gear input shaft.

3. The pure electric vehicle gearbox according to claim 1, characterized in that: The reduction gear comprises: A main reduction gear, which is fixedly sleeved on the driving shaft; A slave reduction gear is loosely mounted on the half shaft and meshes with the main reduction gear; the slave reduction gear is fixedly connected to the differential.

4. The pure electric vehicle gearbox according to claim 1, characterized in that: Also includes: a motor sensor, which is provided on the motor and is used to detect the operating state of the motor; a transmission control unit, configured to control engagement and disengagement of the dual clutch; The transmission control unit further includes an anti-disturbance controller, which outputs a control signal to control the output torque and rotational angular velocity of the motor.

5. A method for controlling a transmission of a pure electric vehicle, for controlling the transmission of a pure electric vehicle according to any one of claims 1 to 4, characterized in that: When the gearbox is in first gear, the first gear clutch is engaged, the second gear clutch is disengaged, and the dual clutch is in the first gear engaged state; power is transmitted from the motor to the first gear driving gear through the first gear clutch in the dual clutch, and then transmitted to the half shaft through the first gear driven gear, the drive shaft, the reduction gear and the differential, thereby driving the wheels; When the transmission is in second gear, the second gear clutch is engaged, the first gear clutch is disengaged, and the dual clutch is in the second gear engaged state; power is transmitted from the motor to the second gear driving gear through the second gear clutch in the dual clutch, and then transmitted to the half shaft through the second gear driven gear, the drive shaft, the reduction gear and the differential, thereby driving the wheels; The shifting process includes: A preparation phase, in which the first gear clutch transmits the motor torque alone and the second gear clutch does not transmit the motor torque; The torque phase is a phase in which the first gear clutch is gradually disengaged, the second gear clutch is gradually engaged, and the first gear power transmission route is switched to the second gear power transmission route; The inertia stage is a stage in which the first gear clutch does not transmit the motor torque, the motor is adjusted to reduce the speed difference between the second gear active part and the second gear driven part of the second gear clutch to a second gear set threshold, and the second gear clutch is fully engaged.

6. The control method of a pure electric vehicle transmission according to claim 5, characterized in that: Also includes: In the preparation stage, after the transmission control unit detects the vehicle upshift signal, it controls the oil pressure of the first gear clutch to be rapidly reduced to the slip friction value, so that the first gear clutch is released from the locked state but still maintains the slip friction state to transmit power; it controls the second gear clutch to be quickly filled with oil to eliminate the idle stroke and reach the critical contact point, so that the second gear clutch reaches a state of being about to engage but not transmitting torque; In the torque phase, the transmission control unit controls the oil pressure of the first gear clutch to continuously decrease to zero, controls the oil pressure of the second gear clutch to gradually increase to the second gear set threshold, and controls the torque of the motor to adjust from the first gear initial value to the second gear set threshold, thereby completing the power transmission route switching; During the inertia stage, the transmission control unit controls the oil pressure of the first-gear clutch to be reduced to zero, and the second-gear clutch is in a slipping state; the anti-disturbance controller adjusts the torque and angular velocity of the motor; when the speed difference between the second-gear active part and the second-gear driven part of the second-gear clutch is less than the second-gear set threshold, the oil pressure of the second-gear clutch is controlled to increase rapidly, the second-gear clutch is fully engaged, and the gear shift operation is completed.

7. The control method of a pure electric vehicle transmission according to claim 6, characterized in that: The control method of the anti-disturbance controller is: Acquire the actual rotational angular velocity of the motor and the output torque of the motor through the motor sensor; Inputting the actual rotational angular velocity of the motor and the output torque of the motor into a linear extended state observer, the linear extended state observer outputting a motor rotational angular velocity observation value and a disturbance estimation value; Obtaining the desired rotational angular velocity of the motor; inputting the desired rotational angular velocity of the motor and the observed value of the rotational angular velocity of the motor into a feedback control module, and the feedback control module outputting a feedback control amount; Inputting the feedback control amount and the interference estimation value into a control amount calculation module, and the control amount calculation module outputs a total control amount; The total control amount is used to control the torque of the motor and the actual rotation angular velocity of the motor to form a closed-loop control.

8. The control method of a pure electric vehicle transmission according to claim 7, characterized in that: The feedback control quantity is: Where, u0 is the feedback control quantity; K p is the proportional gain of the controller; ω d is the desired angular velocity of the motor; is the observed value of the motor rotation angular velocity.

9. The control method of a pure electric vehicle transmission according to claim 8, characterized in that: The total control amount is: Where u is the total control quantity; z2 is the disturbance component of the observation value of the linear extended state observer; I′ m It is the reciprocal of the equivalent moment of inertia of the motor shaft.

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