CN117704024A - Vehicle drive axle with differential active control function and control method thereof - Google Patents
Vehicle drive axle with differential active control function and control method thereof Download PDFInfo
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- CN117704024A CN117704024A CN202410035967.7A CN202410035967A CN117704024A CN 117704024 A CN117704024 A CN 117704024A CN 202410035967 A CN202410035967 A CN 202410035967A CN 117704024 A CN117704024 A CN 117704024A
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- 230000005540 biological transmission Effects 0.000 claims abstract description 23
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H48/00—Differential gearings
- F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60K17/00—Arrangement or mounting of transmissions in vehicles
- B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
- B60K17/16—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of differential gearing
- B60K17/165—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of differential gearing provided between independent half axles
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H48/00—Differential gearings
- F16H48/06—Differential gearings with gears having orbital motion
- F16H48/08—Differential gearings with gears having orbital motion comprising bevel gears
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H48/00—Differential gearings
- F16H48/38—Constructional details
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H48/00—Differential gearings
- F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
- F16H2048/204—Control of arrangements for suppressing differential actions
- F16H2048/205—Control of arrangements for suppressing differential actions using the steering as a control parameter
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Arrangement And Mounting Of Devices That Control Transmission Of Motive Force (AREA)
Abstract
The invention discloses a vehicle drive axle with an active differential control function and a control method thereof, wherein the vehicle drive axle comprises a differential auxiliary motor; a driving wheel; and a transmission for transmitting power to the drive wheels and a planetary gear train for transmitting power from the auxiliary motor to the differential gear; the transmission includes differential gears, side gears, and differential cases, the differential gears being intermeshed with each other and with the respective corresponding side gears, the differential gears being disposed on the differential cases. The auxiliary motor is connected with the differential gear through the planetary gear train. The auxiliary motor can adjust output torque and steering according to the control method, so that active distribution of power at two ends of the drive axle is realized. The invention can assist the vehicle to turn, realize the limited slip of the differential mechanism when the vehicle has a slip trend, play the role of the differential mechanism lock when the vehicle slips, and greatly improve the escaping capability of the vehicle.
Description
Technical Field
The present invention generally relates to a vehicle driving axle with an active control function of a differential mechanism and a control method thereof, and more particularly, to an active control method of a differential mechanism in a complex road environment to provide a vehicle with better drivability.
Background
The power of the engine is transmitted to the drive wheels via transmission means including clutches, gearboxes, propeller shafts and drive axles. Wherein the drive axle is the last assembly of the drive train, and the drive axle generally consists of a speed reducer and a differential.
When the vehicle turns, the turning radii of the inner and outer wheels are different, and therefore, it is required that the rotational speeds of the inner and outer wheels are different and the rotational speed of the outer wheel is higher than the rotational speed of the inner wheel during the turning. Therefore, the differential is a transmission device which can cause the rotation speeds of the inner and outer wheels to be different when the vehicle turns, and reasonably distributes torque to the left and right wheels when the vehicle turns so as to enable the vehicle to smoothly turn.
The main function of the differential is to distribute the driving force transmitted from the power source to the driving wheels on both sides. When the vehicle is traveling in a straight line, both wheels are assigned the same driving force, and therefore both wheels have the same rotational speed. When the vehicle turns, the differential mechanism performs differential so that the left wheel and the right wheel obtain different rotating speeds, thereby ensuring that the vehicle can turn smoothly.
In general, a differential is composed of a planetary gear, a carrier, a differential case, a side gear, and the like, and power input from an engine is transmitted to the differential case, directly applied to the differential case, and then transmitted to left and right half shafts via planetary gears, thereby driving wheels. A typical differential is designed to meet the rotational speed of the left and right axle shafts and a differential case rotational speed equal to twice. When the vehicle runs straight, the rotation speed of the left half shaft and the right half shaft is equal to that of the differential case, and the left wheel and the right wheel are rigidly connected by one shaft. When the vehicle turns, the inner gear of the differential mechanism moves relatively, so that the rotation speed of the outer wheel is increased, and the rotation speed of the inner wheel is reduced.
However, the conventional differential has a significant disadvantage in that when one side wheel slips or spin, the differential transmits most of the power to the slipping or spin wheel, so that the vehicle cannot normally run and a large amount of power is lost. Therefore, in order to prevent this, a limited slip differential has been developed that rigidly connects the left and right axle shafts when the vehicle is slipping, thereby allowing the power to be equally distributed to the wheels on both sides, helping the vehicle break out of the dilemma.
The problems with current differentials are mainly: the limited slip differential requiring manual manipulation is simple in technology, reliable in operation, but expensive in cost, short in service life and inconvenient to use. The active limited slip differential can only play a role when the rotation speed difference of wheels at two sides reaches a set value, and the vehicle slip cannot be prevented.
With the rapid development of motor control technology, the differential can be controlled by the motor. The motor control differential can reduce the impact generated during operation compared with the common mechanical limited slip differential, and can prevent the vehicle from slipping in advance relative to the active limited slip differential.
Disclosure of Invention
In order to solve the problems of the existing limited slip differential, the invention provides a vehicle drive axle with an active differential control function and a control method thereof, so that a vehicle can adjust the working characteristics of the differential under complex road surface environment and variable weather conditions, and the slip trend of the vehicle is judged according to actual conditions, thereby enabling a motor to control the differential to limit slip in advance, and further preventing the vehicle from slipping. In addition, the motor control differential can not only control the differential to prevent skid, but also assist the vehicle to turn, which is a function not possessed by a common differential lock.
According to an aspect of the present invention, there is provided a vehicle drive axle having an active differential control function, the drive axle including an auxiliary motor; the transmission device is a differential mechanism, the output is connected with the half shaft, the input end is connected with the auxiliary motor, and the control unit. And the control unit controls the auxiliary motor to control the transmission device according to the speed of the vehicle and the difference of the rotation speeds of the two wheels.
According to another aspect of the invention, a control method for actively controlling the differential is provided, the rotation speed and direction of the auxiliary motor are regulated according to different conditions, and then the working condition of the differential gear in the differential is controlled, so as to realize the active allocation of the differential to the left and right half axle torque, and the method comprises the following steps:
the current vehicle speed and the rotational speed difference of the wheels at the two sides are determined.
The auxiliary motor assists the differential to differential and drive the differential gear to rotate together when the vehicle speed is not zero and the wheels on two sides have larger rotation speed difference within the set allowable range, and torque is transferred from the low-speed side half shaft to the high-speed side half shaft, so that the steering characteristic of the vehicle is improved. The torque provided by the auxiliary motor increases as the wheel speed difference increases and also decreases as it decreases.
When the vehicle speed is not zero, the wheels on the two sides have larger rotation speed difference and approach to the set allowable critical value, the auxiliary motor can operate to prevent the differential mechanism from differentiating, so that the rotation speed of the differential mechanism is reduced, the slip limiting performance of the differential mechanism is improved in advance, and the vehicle is helped to prevent slipping. The torque provided by the auxiliary motor increases as the wheel speed difference increases and also decreases as it decreases.
When the speed of the vehicle is zero, the wheels on the two sides have larger rotating speed difference and exceed a set value, the auxiliary motor can quickly run to block the differential mechanism from differentiating, so that the rotating speed of the two differential gears is reduced to zero, at the moment, the two half shafts have no rotating speed difference, which is equivalent to rigid connection of the two half shafts, and the torque is evenly distributed to the left half shaft and the right half shaft, so that the vehicle has better anti-skid performance and gets rid of the slipping condition as soon as possible.
Alternatively, when the differential is in a steady state operation, the rotational speed of the differential gear is constant and the sum of the drive torque of the differential gear for all loads is zero. The left and right output shaft torque distribution of the differential can be realized by applying an additional driving torque on the differential gear to change the force applied to the two side half shafts. During operation of the differential, the differential gear is subjected to forces imparted to it by the left and right axle shafts, torque from the left and right axle shafts driving the differential gear, friction drag torque, and additional driving torque. The torque of the differential gear driven by the left half shaft and the right half shaft and the magnitude and the direction of the additional driving torque influence the working characteristics of the differential, so that different control methods are adopted for the additional driving torque, and various additional functions of the differential can be realized.
When the directions of the torque of the differential gear driven by the left and right side gears and the additional driving torque are opposite, the additional driving torque counteracts the driving torque on the differential gear, the rotation speed of the differential gear is reduced, and the rotation speed difference of the side gears is reduced, so that the limited slip or differential lock function is realized. In this case, when the torque of the differential gear driven by the left and right half shafts is greater than the additional driving torque, the driving torque difference of the two half shafts is reduced, the rotation speed difference of the left and right half shafts is reduced, and the differential has a slip limiting function; when the torque of the differential gear driven by the left half shaft and the right half shaft is equal to the additional driving torque, the two half shafts are not different in rotation speed, and are equivalent to rigid connection of the two half shafts; when the torque of the left and right axle shafts driving the differential gear is smaller than the additional driving torque, the differential gear will rotate in the opposite direction, which is not compatible with practical applications.
When the directions of the torque of the left and right side gear drive differential gears and the additional drive torque are the same, the additional torque and the torque of the left and right side drive differential gears together drive the differential gears to rotate and transfer the torque from the low speed half shaft to the high speed half shaft, thereby improving the steering characteristics of the vehicle. In this case, when the torque of the left and right axle shaft driving differential gears is greater than the additional driving torque, the magnitude of the force applied to the axle shafts by the differential gears of the two side axle shafts is reduced, and part of the torque is transferred from the low speed side to the high speed side, but the driving force obtained by the high speed side wheels is still smaller than that obtained by the low speed side wheels; when the torque of the differential gears driven by the left and right half shafts is equal to the additional driving torque, the force of the differential gears acting on the two half shafts on the two sides to the half shafts becomes zero, part of the torque is transferred from the low-speed side to the high-speed side, and the torque obtained by the wheels on the two sides is equal; when the torque of the differential gears driven by the left and right half shafts is smaller than the extra driving torque, the direction of the differential gears acting on the two half shafts on the two sides changes to the direction of the force of the differential gears on the half shafts, part of the torque is transferred from the low-speed side to the high-speed side, the differential gears assist in driving the wheels on the high-speed side, and the outer wheels obtain larger driving force than the inner wheels under the turning working condition, so that the turning radius of the vehicle is reduced.
Preferably, the additional drive torque in the method is provided by an auxiliary motor.
Preferably, the method measures the speed of the vehicle and the difference in rotational speeds of the two wheels over a predetermined time interval.
Optionally, the selected method is done in advance at the time of delivery of the car and controls the steering of the auxiliary motor and the torque provided for different vehicle speeds and wheel speed differences on both sides.
The active control method of the differential mechanism can optimize the working performance of the differential mechanism of the automobile in real time, thereby improving the drivability of the automobile, improving the turning performance and preventing the automobile from skidding.
Drawings
The foregoing and other aspects of the invention will be more fully understood from the following detailed description, taken together with the accompanying drawings. It is noted that the proportions of the various figures may be different for clarity of illustration, but this does not affect the understanding of the invention. In the drawings:
FIG. 1 schematically illustrates a block diagram of a differential active control system;
FIG. 2 schematically illustrates a schematic view of one embodiment of a vehicle drive axle having an active differential control function as shown in FIG. 1;
fig. 3 schematically shows a flow chart of a method for active control of a differential according to the invention.
Detailed Description
Features that are structurally identical or functionally similar are denoted by the same reference numerals in the various figures of the present application.
Fig. 1 schematically shows a block diagram of a vehicle drive axle assembly with active differential control according to the present invention. The system comprises a power source 1 for powering the whole transmission 3. The auxiliary motor 2, the auxiliary motor 2 being always connected to components in the transmission 3, influences the power distribution of the transmission 3 to the two-sided drive wheels 4 under the control of the vehicle control unit 5. The vehicle control unit 5 may control the auxiliary motor 2 and monitor the rotational speed difference of the driving wheels 4 on both sides, respectively, for example, may obtain the required real-time control of the magnitude and direction of the output torque of the auxiliary motor 2 according to the monitored rotational speed difference of the driving wheels 4 on both sides.
In addition, the power source of the present invention may be a fuel engine or an electric motor, and therefore, it should be clear to those skilled in the art that the vehicle with the differential control function referred to in the present application may be either a fuel vehicle or an electric vehicle.
As shown in fig. 2, in the transmission, the side gear 18 is meshed with the differential gear 1, and the differential gear 1 is meshed with the differential gear 4. The differential gear 4 is fixedly connected with the planetary gear 5, the differential gear 4 is meshed with the side gear 16, the planetary gear 5 is meshed with the gear ring 6 and the gear ring 14, the gear ring 6 is further meshed with the planetary gear 7, the planetary gear 7 is meshed with the sun gear 12, the sun gear 12 is fixedly connected with the vehicle body, the planetary gear 7 is connected with the planet carrier 8, the gear ring 14 is meshed with the planetary gear 9, the planetary gear 9 is meshed with the sun gear connected with the auxiliary motor 11, and the planetary gear 9 is connected with the planet carrier 8. The differential gear 1 and the differential gear 4 are both mounted on the differential case 15. So that torque can be transmitted from the differential case 15 to the driving wheels 10 and 19 via the differential gear 1 and 4, the side gears 16 and 18. Wherein the parameters of the planetary gear 7 and the planetary gear 9 are the same, and the parameters of the sun gear 12 and the sun gear connected with the auxiliary motor 11 are the same.
When the rotational speeds of the driving wheel 10 and the driving wheel 19 are the same, the differential gear 1 and the differential gear 4 only rotate in the revolution along with the differential case and do not rotate, then the planetary gear 5 is equivalent to being fixedly connected with the gear ring 14 and the gear ring 6, so that the movement conditions of the planetary gear 6 and the planetary gear 8 are the same, the movement conditions of the sun gear 12 and the sun gear connected with the auxiliary motor 11 are the same, and the rotational speed of the sun gear connected with the auxiliary motor 11 is zero because the fixed connection rotational speed of the sun gear 12 and the vehicle body is zero. Thereby ensuring that the auxiliary motor 11 does not operate when the differential gear 1 and the differential gear 4 do not spin. When the auxiliary motor 11 is operated, the torque of the auxiliary motor 11 is transmitted to the planetary gears 9, then to the ring gear 14 from the planetary gears 9, then to the planetary gears 5 from the ring gear 14, and finally to the side gears 16 and 18 from the differential gear 4.
According to the differential active control method, the vehicle control unit of the automobile can determine the magnitude and the direction of the output torque of the auxiliary motor according to the determined speed of the automobile and the rotation speed difference of wheels on two sides.
For the conventional differential lock, the rotational speed difference of driving wheels at two sides is generally limited after the automobile slips, and the conventional differential lock generally generates a certain impact in the action process and cannot prevent the automobile from slipping. The active control method of the differential mechanism can reduce impact, prevent skidding in time and improve turning performance when the vehicle turns.
Fig. 3 schematically illustrates a flow chart of a method of active differential control according to one embodiment of the invention.
First, in step S1, the current speed of the automobile and the rotational speed difference of the driving wheels on both sides are determined.
In step S2, it is determined whether the differential auxiliary motor needs to operate according to the current operating condition. Whether the auxiliary motor is operated or not may be determined by factors such as the current vehicle speed, the difference in rotational speeds of the driving wheels on both sides, the position of the accelerator pedal, the position of the brake, the cruise setting, the state of the vehicle uphill or downhill, etc., which may be done by the vehicle control unit, for example.
If the determination result of step S2 is yes, the vehicle control unit determines whether the rotational speed difference of the driving wheels on both sides of the vehicle is within the allowable range based on the rotational speed difference of the driving wheels on both sides in step S3.
If the determination in step S3 is yes, step S4 may determine that the steering of the auxiliary motor is to assist the differential to perform the differential, and then calculate the output torque of the auxiliary motor according to the rotational speed difference and the vehicle speed.
The specific implementation steps of step S4 are as follows.
First, the rotation of the planetary gear 5 connected to the auxiliary motor is determined based on the positive and negative of the wheel speed difference deltan between the two sidesAnd steering to thereby determine the steering of the auxiliary motor output torque. The torque output by the auxiliary motor is larger as the rotation speed difference is larger and the maximum torque T can be output by the auxiliary motor max For the determination of the value, the output torque of the auxiliary motor at this time can be calculated by linear interpolation based on the current rotational speed difference.
For example, assume that the difference in rotational speed between the two sides is Δn 1 And Deltan 1 <0, by Δn=n 2 -n 1 It can be seen that when the rotational speed difference is less than zero, the direction of rotation of the planet wheel 5 is opposite to the direction of rotation of the wheels on the two sides. Let Deltan' 1 ＝|Δn 1 I, due to Deltan' 1 At a set rotational speed difference delta n min1 And Deltan max1 The auxiliary motor is required to assist the differential, so that the direction of the output torque of the auxiliary motor can be determined to be opposite to the direction of the planetary gear, namely the direction of the two-side wheels. Auxiliary motor output torque t=t max ×(Δn′ 1 -Δn min1 )/(Δn max1 -Δn min1 ). Further assume an 1 ＝-400r，Δn min1 ＝200r，Δn max1 ＝800r，T max If the torque of the auxiliary motor is equal to the steering direction of the wheels, the torque of the auxiliary motor is determined to be 200 N.m, and the torque of the auxiliary motor is determined to be T=T max ×(Δn′ 1 -Δn min1 )/(Δn max1 -Δn min1 ) 200× (400-200)/(800-200) =66.67 n·m. Wherein n is 1 Indicating the rotation speed of the differential gear 1, n 2 Indicating the rotation speed of the differential gear wheel 4, delta n min1 To assist the motor in assisting the lowest rotational speed differential in starting operation, delta n max1 To assist the motor to assist the differential to work, T is the maximum rotation speed difference max The maximum output torque of the auxiliary motor is a parameter which is already determined in advance by the auxiliary motor, for example, is stored in a corresponding auxiliary motor memory, and is directly called when needed.
If the result of the step S2 is "no", the step S1 is executed after a period of time.
If the determination result in step S3 is "no", step S5 may determine that the auxiliary motor assists the differential to perform limited slip, and then calculate the output torque of the auxiliary motor according to the rotational speed difference and the vehicle speed.
The specific steps of step S5 are as follows.
The state of the vehicle is firstly judged based on the vehicle speed, if the vehicle speed is zero, the slip of the vehicle is indicated, and then the steering of the planetary gear 5 connected with the auxiliary motor is judged according to the positive and negative of the wheel rotation speed difference delta n at the two sides, so that the steering of the output torque of the auxiliary motor is determined. The magnitude of the output torque required by the auxiliary motor should not cause the differential gear 4 to rotate. The torque M input to the planetary gear by the auxiliary motor should satisfy M d -M f ≤M≤M d -M f M=t/i. Wherein M is d For driving torque acting on differential gear 4, M f For the friction torque acting on the differential gear 4, T is the auxiliary motor output torque and i is the transmission ratio of the planetary gear train. Due to M when the wheel slips d Is very small, so take m=m f ＝K×T 0 2, wherein K is the locking coefficient of the differential, T 0 Torque is input to the differential. If the vehicle speed is not zero, the slip trend of the vehicle is indicated, and then the steering of the planetary gear 5 connected with the auxiliary motor is judged according to the positive and negative of the wheel rotation speed difference delta n at the two sides, so that the steering of the output torque of the auxiliary motor is determined. Since the torque required to be output by the assist motor is inversely smaller as the rotational speed difference is larger when the input power is unchanged, the output torque of the assist motor is set to the minimum value T when the wheels are fully slipped min Because the auxiliary motor can output the maximum torque T max The output torque of the auxiliary motor at this time can be calculated by linear interpolation based on the current rotation speed difference.
For example, when the vehicle speed is equal to zero, the difference in rotation speed of the driving wheels at both sides is delta n 2 And Deltan 2 <0, judging that the vehicle has slipped according to the condition that the vehicle speed is equal to zero and the rotation speed difference of the driving wheels at two sides is larger than the allowable range, and then determining that delta n=n 2 -n 1 It is known that when the rotational speed difference is less than zero, the planetary gear 5 rotates in the opposite direction to the slipping wheel. Let Deltan' 2 ＝|Δn 2 I, due to Deltan' 2 The auxiliary motor assists the differential to limit slip when the set rotation speed difference is exceeded, so that the output torque direction of the auxiliary motor and the rotation of the planetary gear can be determinedThe same direction, i.e. opposite to the direction of the high-speed turning wheel. Torque t=k×t of the auxiliary motor max 2/i. Further, assuming that the vehicle speed is zero, the rotation speed difference of the driving wheels at two sides is delta n 2 ＝-2000r，K＝0.05，T max When the torque output from the assist motor is equal to or greater than 2000n·m, i=1, the direction of the torque output from the assist motor can be determined to be opposite to the wheel steering, and the torque output from the assist motor t=k×t max 2/i=0.05×2000/2/1=50n·m. Wherein T is max The input torque of the differential mechanism in the first gear of the automobile is i is the transmission ratio of the planetary gear train, and K is the locking coefficient of the differential mechanism. The input torque and the locking coefficient of the differential in first gear of the motor vehicle are parameters which have been determined in advance, for example stored in a corresponding memory, and can be directly called if necessary.
For another example, when the vehicle speed is not zero and has a certain value, the difference in rotation speed of the driving wheels at both sides is delta n 3 And Deltan 3 <0, judging that the vehicle has a slip trend and is in a set rotational speed difference delta n according to the fact that the vehicle speed is not zero and the rotational speed difference of the driving wheels at two sides is larger than an allowable range min2 And Deltan max2 Between, again by Δn=n 2 -n 1 It is known that when the rotational speed difference is less than zero, the planetary gear 5 rotates in the opposite direction to the slipping wheel. Let Deltan' 3 ＝|Δn 3 I, due to Deltan' 3 The auxiliary motor assists the differential to limit slip beyond the set rotational speed differential, so that it can be determined that the direction of the auxiliary motor output torque should be the same as the planetary gear steering, i.e., opposite to the high speed rotating wheel steering. Torque t=t to be output by the assist motor min +K×(T max -T min )×(Δn max2 -Δn 3 )/(Δn max2 -Δn min2 ). Further, assuming that the vehicle speed is not zero, the rotation speed difference of the driving wheels at two sides is delta n 3 ＝-1600r，K＝0.05，Δn min2 ＝1200r，Δn max2 ＝2000r，T min ＝50N·m，T max When 200n·m, i=1, it can be determined that the direction of the assist motor output torque is opposite to the wheel steering, and the assist motor output torque t=t min +K×(T max -T min )×(Δn max2 -Δn 3 )/(Δn max2 -Δn min2 ) =50+ (200-50) × (2000-1600)/(2000-1200) =125 n·m. Wherein T is max For the input torque of the differential at this time, K is the locking coefficient of the differential and i is the gear ratio of the planetary gear set, as determined by the vehicle control unit.
After the magnitude and direction of the output torque of the auxiliary motor are determined, step S6 is performed to control the magnitude and direction of the output torque of the auxiliary motor.
Therefore, no matter the automobile turns, slips or has a slip trend, the auxiliary motor can be timely controlled according to the differential auxiliary motor control method, so that the drivability of the automobile is improved by actively controlling the performance of the differential, and the escaping capability of the automobile is greatly improved.
The method can be completed in real time in a drive control system, namely, the magnitude and the direction of the output torque of the auxiliary motor are judged according to the actually measured speed and the rotation speed difference of wheels at two sides at a certain time interval, and then the process shown in fig. 3 is repeated continuously, so that the differential auxiliary motor control method can run efficiently in real time according to the real working condition.
Of course, for vehicles that cannot provide real-time calculations, it is also possible to simulate various conditions before the active differential control system of the present invention leaves the factory, then formulate a control strategy in the manner shown in fig. 3, and store the control strategy in the vehicle control unit. When the automobile actually runs, the control strategy stored in advance is called to control the auxiliary motor control differential system according to the working condition monitored in real time.
Although specific embodiments of the invention have been described in detail herein, they are presented for purposes of illustration only and are not to be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications can be made without departing from the spirit and scope of the invention.
Claims (14)
1. A vehicle drive axle with active control function of differential mechanism and control method thereof, the vehicle drive axle comprises a differential mechanism auxiliary motor; a driving wheel; a transmission for transmitting power to the drive wheels; the transmission device comprises differential gears and side gears, the differential gears are meshed with each other and with the corresponding side gears, and the auxiliary motor is connected with the differential gears through a planetary gear train. The auxiliary motor is capable of adjusting output torque and steering according to the control method to actively control the differential.
2. A device according to claim 1, characterized in that in the transmission the side gear 18 is in engagement with the differential gear 1 and the differential gear 1 is in engagement with the differential gear 4. The differential gear 4 is fixedly connected with the planetary gear 5, the differential gear 4 is meshed with the side gear 16, the planetary gear 5 is meshed with the gear ring 6 and the gear ring 14, the gear ring 6 is further meshed with the planetary gear 7, the planetary gear 7 is meshed with the sun gear 12, the sun gear 12 is fixedly connected with the vehicle body, the planetary gear 7 is connected with the planet carrier 8, the gear ring 14 is meshed with the planetary gear 9, the planetary gear 9 is meshed with the sun gear connected with the auxiliary motor 11, and the planetary gear 9 is connected with the planet carrier 8. The differential gear 1 and the differential gear 4 are both mounted on the differential case 15. So that torque can be transmitted from the differential case 15 to the driving wheels 10 and 19 via the differential gear 1 and 4, the side gears 16 and 18. Wherein the parameters of the planetary gear 7 and the planetary gear 9 are the same, and the parameters of the sun gear 12 and the sun gear connected with the auxiliary motor 11 are the same.
3. The transmission according to claim 1, wherein when the rotational speeds of the driving wheel 10 and the driving wheel 19 are the same, the differential gear 1 and the differential gear 4 are only rotated with the differential case and are not rotated, and then the planetary gear 5 is fixedly connected with the ring gear 14 and the ring gear 6, so that the movement of the planetary gear 6 and the planetary gear 8 is the same, the movement of the sun gear 12 and the sun gear connected with the auxiliary motor 11 is the same, and the rotational speed of the sun gear connected with the auxiliary motor 11 is zero because the rotational speed of the sun gear 12 fixedly connected with the vehicle body is zero. Thereby ensuring that the auxiliary motor 11 does not operate when the differential gear 1 and the differential gear 4 do not spin. When the auxiliary motor 11 is operated, the torque of the auxiliary motor 11 is transmitted to the planetary gears 9, then to the ring gear 14 from the planetary gears 9, then to the planetary gears 5 from the ring gear 14, and finally to the side gears 16 and 18 from the differential gear 4.
4. A transmission according to claim 2, characterised in that the ring gear 7 has both an inner ring gear and an outer ring gear.
5. The method according to claim 1, wherein the invention provides a vehicle drive axle with an active differential control function and a control method thereof, so that the vehicle can actively control the differential under complex road surface environment and variable weather conditions, thereby improving the drivability of the vehicle.
6. The method of claim 1, wherein the control method adjusts the rotation speed and direction of the motor according to different conditions, thereby controlling the working condition of the planetary gears in the differential, and realizing the active allocation of the differential to the left and right axle shaft torque, the method comprises the following steps:
the current vehicle speed and the rotational speed difference of the wheels at the two sides are determined.
The auxiliary motor assists the differential to differential in a speed range which is not zero and has a large rotation speed difference between wheels at two sides, the differential is driven to rotate together, and torque is transferred from a low-speed side half shaft to a high-speed side half shaft, so that the steering characteristic of the vehicle is improved, and the differential is controlled to assist in turning on a rugged multi-curve road. The torque provided by the motor increases as the wheel speed difference increases and also decreases as it decreases.
When the speed of the vehicle is not zero, the wheels on two sides have larger rotation speed difference and exceed a set value, the auxiliary motor blocks the differential mechanism from differentiating, so that the rotation speed of the differential gear is reduced, the slip limiting performance of the differential mechanism is improved in advance, and the vehicle is helped to prevent slipping in rainy and snowy weather and on complex road surfaces. The torque provided by the auxiliary motor at a given power level is reduced as the difference between the rotational speeds of the wheels on both sides increases, and also increases as the difference decreases.
When the speed of the vehicle is zero, the wheels on the two sides have larger rotating speed difference and exceed a set value, the auxiliary motor rapidly runs to prevent the differential mechanism from differentiating, so that the two differential gears do not rotate, at the moment, the two half shafts have no rotating speed difference, which is equivalent to rigid connection of the two half shafts, and the torque is evenly distributed to the left half shaft and the right half shaft, so that the vehicle has better anti-skid performance and gets rid of the slipping condition as soon as possible.
7. The method of claim 6, wherein the rotational speed of the differential gear is constant when the differential is in a steady state operation, and the sum of all loads to the drive torque of the differential gear is zero. The left and right output shaft torque distribution of the differential can be realized by applying an additional driving torque on the differential gear to change the force applied to the two side half shafts. During operation of the differential, the differential gear is subjected to torque, friction torque and additional drive torque from the left and right axle shafts driving the differential gear. The torque of the differential gear driven by the left half shaft and the right half shaft and the magnitude and the direction of the additional driving torque influence the working characteristics of the differential, so that different control methods are adopted for the additional driving torque, and various additional functions of the differential can be realized.
8. The method of claim 7, wherein the additional drive torque is provided by an auxiliary motor.
9. The method of claim 6, wherein the method measures the running speed of the vehicle and the difference in rotational speeds of the two wheels at predetermined intervals.
10. The method of claim 6, which is completed in advance at the time of shipment of the automobile and controls steering of an auxiliary motor and the supplied torque for different vehicle speeds and both-side wheel speed differences.
11. The method of claim 10, wherein the control unit controls steering and torque of the motor.
12. The method of claim 6, according to another aspect of the present invention, there is also provided a vehicle differential active control system, the system comprising an auxiliary motor; the transmission device is a driving axle, the output of a differential mechanism in the transmission device is connected with a half shaft, the input end of the differential mechanism is connected with an auxiliary motor, and the control unit. And the control unit controls the auxiliary motor to control the differential mechanism according to the speed of the vehicle and the difference of the rotation speeds of the two wheels.
13. The method of claim 12, wherein the transmission is a gear transmission.
14. A vehicle drive axle with active control function of differential mechanism and control method thereof, the vehicle drive axle comprises a differential mechanism auxiliary motor; a driving wheel; and a transmission for transmitting power to the drive wheels and a planetary gear train for transmitting torque of the auxiliary motor to the differential gear; the transmission device comprises differential gears and side gears, the differential gears are meshed with each other and with the corresponding side gears, and the auxiliary motor is connected with the differential gears through a planetary gear train. The auxiliary motor is capable of adjusting output torque and steering according to the control method to actively control the differential. The vehicle is characterized by being a fuel oil vehicle, a hybrid electric vehicle and a pure electric vehicle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410035967.7A CN117704024A (en) | 2024-01-10 | 2024-01-10 | Vehicle drive axle with differential active control function and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410035967.7A CN117704024A (en) | 2024-01-10 | 2024-01-10 | Vehicle drive axle with differential active control function and control method thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117704024A true CN117704024A (en) | 2024-03-15 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202410035967.7A Pending CN117704024A (en) | 2024-01-10 | 2024-01-10 | Vehicle drive axle with differential active control function and control method thereof |
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| Country | Link |
|---|---|
| CN (1) | CN117704024A (en) |
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- 2024-01-10 CN CN202410035967.7A patent/CN117704024A/en active Pending
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