RU2340472C2 - Method for vehicle driveline control - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: in transmission there is possibility to individually change speed ratio and torsion torques distribution among separate branches of driveline power flows. The method consists in optimisation of driveline operation by means of arranging of certain control algorithms for speed ratios and torsion torques distribution among various branches of driveline power flows.

EFFECT: individual distribution of torsion torques ratio among separate vehicle wheels and elimination of power circulation phenomenon.

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Description

Vehicle transmission control method

The invention relates to transport engineering, namely to transmissions of vehicles, and can be applied mainly on biaxial, triaxial and four-axle vehicles intended for use in any road conditions and off-road, as well as in conditions requiring increased maneuverability. In more detail, the present invention relates to a method for controlling the distribution of the torque ratio between the wheels of a vehicle.

US patent No. 4987967, which is the closest prototype to the invention (four-wheel vehicle control method), disclosed an aggregate for changing the distribution of the torque ratio. The described unit distributes engine torque between the front wheels and rear wheels, in the required order, through a differential mechanism, and contains two variators that transmit torque to the axles of the front and rear wheels, respectively. The unit can change the speed ratio between the front wheels and the rear wheels and adjust the distribution of the torque ratio. The differential mechanism of the unit absorbs all the differences in rotation speeds caused by the mismatch of the speed ratio. Moreover, the unit includes sensors that detect the conditions of movement of the vehicle, and controls the distribution of the ratio of torque in accordance with the detected conditions of movement.

However, this method does not allow for individual distribution of the torque ratio between the individual wheels of the vehicle. The described method does not allow to eliminate the phenomenon of "power circulation" that occurs in the units and nodes of the transmission with locked differentials or lack thereof, because it is impossible to adjust the angular velocity and the input torque of each wheel separately.

Such a transmission provides stepless regulation of traction on wheels, however, it has a small gear ratio range and is capable of transmitting a relatively small torque, which makes it difficult to use it on heavy vehicles.

The present invention has been developed, taking into account the foregoing, to overcome the aforementioned obstacles. Thus, an object of the invention is a method for precisely controlling the distribution of the torque ratio between all wheels of a vehicle.

Accurate control of the distribution of the ratio of torque over the wheels of the vehicle can be achieved using the transmission module to control the distribution of the ratio of torque.

The present invention is aimed at expanding the functionality of transmission control, reducing load, increasing efficiency, increasing the unification of units and assemblies, increasing compactness and reducing the complexity of controlling a continuously variable transmission of a vehicle.

The solution of the tasks is achieved by the fact that the continuously variable transmission of the vehicle (figure 1) is a combination of compact unified modules. A continuously variable transmission of a vehicle consists of a power unit, including a power unit 1 with an electronic control unit and a speed sensor 14, and a unit that allows breaking or transforming the power flow 2 (torque converter or clutch), a transfer case 3 with or without differential (for vehicles means with the number of driving axes more than one), shafts connecting the transmission units to each other, center differential 4 with devices for their remote locking, which may not be be, an electronic transmission control unit 11, a fuel pedal position sensor 12, a steering wheel angle measurement sensor 13, a driving mode switch 19, two longitudinal and lateral acceleration sensors of the vehicle 18 located at the edges of the vehicle, and one or more transmission modules, consisting of a central gear reducer 5 with a differential and a device for remote locking of this differential, two safety clutches 6, two variators 7 with metal flexible elements with devices for changing the running radius of the driving pulleys 21, two additional gearboxes 8, which may not be there, two half shafts 10, two wheel gears 9, which may not be there, two torque measuring sensors 17 located between the central gearbox and the propulsion, two speed sensors of the drive variator pulley 16 located in front of the drive variator pulley and two sensors of the drive speed 15. The torque from the power unit is fed to the transfer case 3, which distributes There is torque on the transmission modules. In the transmission module, torque is supplied to the input shaft of the central gearbox. The leading elements of the safety clutches are connected to each of the two output shafts of the latter, and the drive variator pulleys are installed on their driven elements. The driven pulleys of the variators, in turn, transmit torque through additional gears to the wheel gears via half shafts, then to the propulsors, due to which longitudinal forces arise in the spot of contact of the wheel with the supporting surface, causing the vehicle to move.

Each transmission module contains two safety clutches necessary to protect the variators and other transmission units from overloads that may occur when the vehicle is moving (for example, if one of the wheels loses contact with the ground).

If necessary, expanding the range of changes in torque can be achieved as a result of applying (an additional gearbox, which can be combined with the RC) of a two- or three-stage RC, in which, in order to reduce the torque passing through the variator, the higher stages are made accelerating, and the lower - with a gear ratio close to one. Inter-axle and inter-wheel differentials provide rotation of wheels with different angular speeds regardless of the load on the wheels, the path traveled by each of the wheels, tread wear, tire pressure, etc. Thanks to the use of these differentials, it is possible to equip the vehicle's brake control with an anti-lock system and reduces the load on the control system when driving with unlocked differentials.

The vehicle speed and traction on wheels are controlled by synchronously changing the running radius of the pulleys of all variators 7, set by an electronic control unit 11 that processes the signal from the position sensor of the fuel pedal 12, the sensors for measuring torque 17, the engine speed sensors 14 and the wheels vehicle 15, speed sensors of driving variator pulleys 16, longitudinal and lateral acceleration sensors of vehicle 18. Differential agr mechanism gata absorbs any differences in the rotational speeds caused by mismatched speed ratios. When driving in turns, information is also removed from the sensor for measuring the angle of rotation of the steering wheel 13.

The installation of individual variators near the drive wheels allows for optimal distribution of torque along the axles and wheels, providing the best operational properties, for example, controllability, stability, economy, etc., carried out by correcting the gear ratios of individual variators, which can be performed both with unlocked and and with locked differentials. In addition, this reduces the torque transmitted by one variator, while increasing the torque developed by the power plant, which allows the use of continuously variable V-belt transmission not only on light, but also on heavy vehicles.

Due to a wide enough range of stepless regulation of traction on wheels and, accordingly, vehicle speed, it becomes possible to ensure the operation of the power plant at maximum power, minimum fuel consumption, etc.

Moreover, a method for controlling the distribution of the torque ratio includes a detection step and a control step. At the detection step, sensors are collected using sensors. At the control step, the torque ratio is distributed in accordance with the information received.

To explain the principle of torque control on individual wheels or axles with unblocked differentials, we consider two front axles of a multiaxial vehicle with differential coupling between the wheels of these axles. Suppose that the center and center differential are symmetrical and are characterized by low internal friction. In order to simplify the following considerations, we assume that the rolling radii of the wheels are independent of the applied torque and are equal to each other, and the losses in the transmission units do not depend on the mode of their operation.

With the rectilinear movement of the vehicle with a constant speed V _tf on a flat bearing surface, the absence of skidding of the wheels and the equality of gear ratios of all individual variators, the semi-axial gears of all the cross-axle differentials will rotate at the same speeds

where ω _lshk ; ω _pshk ; ω _dk - respectively, the angular rotation speeds of the left and right _semi - _axial gears and differential housing of the k-th axis;

u _cr - gear ratio of the wheel gear;

u _var - gear ratio of the variator.

Moments applied to the left and right wheels of the first axis will be equal

- моменты, подводимые к левому и правому колесу и к корпусу дифференциала соответственно;Where

- moments supplied to the left and right wheels and to the differential housing, respectively;

η _cr - the efficiency of the wheel gear;

η _var - the efficiency of the variator.

With a simultaneous increase in the gear ratio of the variator of the right wheel of the first axis by Δu _var1 and a decrease in the gear ratio of the variator of the left wheel of the first axis by the same value Δu _var1, equality (1) is violated, and the angular speeds of rotation of the half-axis gears of the left and right wheels of the first axis will become, respectively are equal

- угловые скорости вращения левой и правой полуосевых шестерен колес первой оси после коррекции передаточных чисел вариаторов первой оси.Where

- angular rotation speeds of the left and right semi-axial gears of the wheels of the first axis after the correction of the gear ratios of the variators of the first axis.

Thus, the right semi-axial gear of the front axle will accelerate, and the left one will slow down. However, the rotation speed of the cross-axle differential housing of the first axis will remain the same

Despite the fact that the symmetrical cross-axle differential divides the moment between the semi-axial gears equally, the moment supplied to the right wheel of the first axle will be increased in accordance with the increased gear ratio of the transmission section between the inter-wheel differential and the drive wheel

and the moment on the left wheel is reduced

at a constant value of torque supplied to the front axle

где

- соответственно моменты, подводимые к левому и правому колесу и к корпусу дифференциала после коррекции передаточных чисел вариаторов первой оси (фигура 2).

Where

- respectively, the moments supplied to the left and right wheels and to the differential case after correcting the gear ratios of the variators of the first axis (figure 2).

With a simultaneous increase in the gear ratios of both CVTs of the first axis by Δu _var and a decrease in gear ratios of both CVTs of the second axis by the same Δu _{var, the} angular rotational speeds of the drive shafts transmitting torque to the first and second drive axles will increase and decrease accordingly and will be equal to

- угловые скорости вращения приводных валов, передающих крутящий момент к первой и второй оси соответственно после коррекции передаточных чисел вариаторов первой и второй оси;Where

- angular rotational speeds of the drive shafts transmitting torque to the first and second axis, respectively, after correcting the gear ratios of the variators of the first and second axis;

u _cr - the gear ratio of the Central gear.

The angular speed of rotation of the center differential housing will remain unchanged

- угловые скорости вращения корпуса межосевого дифференциала, распределяющего крутящий момент между первой и второй осью, до и после коррекции передаточных чисел вариаторов первой и второй оси соответственно.Where

- angular rotation speeds of the housing of the center differential, distributing torque between the first and second axis, before and after the correction of gear ratios of the variators of the first and second axis, respectively.

Since the moment is divided equally in the symmetric center axle and interwheel differentials, the moment supplied to the wheels of the first axle will be increased in accordance with the increased gear ratio of the transmission section between the drive wheel and the center differential (figure 3) and the moments on the left and right wheels will be equal

and to the wheels of the second axis - reduced

Similarly, the distribution of the ratio of torque between the bogies of the vehicle is regulated (figure 4).

Improving the fuel economy of a vehicle is achieved, firstly, by operating the power plant at the minimum fuel consumption mode, which is ensured by the selection of the appropriate stage in the transfer case and the average gear ratio of all vehicle variators (the average gear ratio of the variator of the vehicle), and, secondly, by correcting the gear ratios of the variators so that when moving a single vehicle at a constant speed, each th wheel is freewheeling when the time supplied to any one of the wheels is the rolling resistance moment of the wheel. The step selection in the transfer case and the gear ratios of the individual variators is carried out by the electronic control unit 11 based on information received from the position sensor of the fuel pedal 12, the torque sensors 17, the longitudinal and lateral acceleration sensors 18, the steering angle sensor 13, the frequency sensors rotation of the crankshaft of the engine 14 and movers 15.

The transition from a mode of operation that provides minimum fuel consumption to a mode of movement at maximum speed is made by the driver forcibly using switch 19 or automatically. Switching to other modes, such as dynamic stabilization mode, is done automatically.

When the vehicle is moving on bends in order to reduce the likelihood of wheel slipping, the gear ratios of the CVTs simultaneously increase, which are external to the center of rotation of the wheel, and accordingly the thrust increases on these wheels, which are most loaded with vertical force, and on the internal unloaded wheels, as a result of reduction of gear ratios of the corresponding CVT traction is reduced.

If the demolition of the front axles or skidding of the rear axles still occurs, then in the dynamic stabilization mode, the control system operates as follows.

Firstly, the moment supplied to the sliding axles is reduced, and the moment supplied to the non-slip axes is increased, for which the gear ratio is reduced in the variators of the sliding axles, and is increased in the variators of the non-slip axes.

Secondly, the torque is redistributed between the wheels of each of the axles so that the moment created by the traction forces of the wheels of one axis prevents the vehicle from turning. To do this, when the front wheels are demolished on all axles or only on non-slip axles, the gear ratios of the CVTs located along the side of the vehicle in the direction of which the demolition is further increased and the gear ratios of the CVTs along the other side are reduced. When the rear axles are skidded on all axles or only on non-slip axles, the gear ratios of the CVTs located along the side in which direction the vehicle skids are additionally reduced and the gear ratios of the variators of the other side are increased.

Thirdly, if necessary, the torque developed by the engine is reduced and the engine speed is reduced.

Differentials are locked either by the driver manually, using switch 19, or automatically by the electronic control unit 11 when wheel slip is detected.

Thanks to the application of this method, it becomes possible to regulate the angular speed and input torque of each wheel individually and with locked differentials, therefore the continuously variable transmission of the vehicle is able to eliminate the phenomenon of “power circulation” that occurs in the units and components of the transmission.

To prove this fact, it is enough to consider the elimination of the phenomenon of “power circulation” on the example of a two-wheeled bicycle making a curvilinear movement, the wheels of which are driven by the same chain through sprockets of the same diameter, since the essence of the method for eliminating this phenomenon is similar for all cases and does not depend on the number wheels and their relative position.

Assumptions made in consideration:

1. Do not take into account the coefficients of wheel drive.

2. The total moment applied to the transmission during the passage of the entire curved section of the trajectory does not change.

3. The rolling radius of the front wheel is equal to the rolling radius of the rear wheel.

So, we find the torques acting on both wheels at different angles of rotation of the front wheel. To do this, we will simulate the rotation of the front wheel by changing the rolling radii of both wheels by an amount depending on the angle of rotation, so that the sum of the radii of the wheels does not change (the condition is imposed by the nature of the phenomenon to which the invention is directed).

X - the value by which it is necessary to change the rolling radii of the wheels to simulate the rotation of the bicycle;

rp ₀ is the rolling radius of the front wheel;

rz ₀ is the rolling radius of the rear wheel;

θ is the angle of rotation of the wheel;

rkp ₀ = rp ₀ + X;

rkp ₀ - modified radius of the front wheel;

rkz ₀ = rz ₀ -X;

rkz ₀ - the changed rolling radius of the rear wheel.

Since the characteristic feature of the drive is the equality of the angular velocities of the front and rear wheels, their rolling radii will become equal, and their increments are compensated by spinning or slipping the wheels in different directions of rotation. Find the real rolling radius, adjusted for the action of the applied torque:

rk is the real rolling radius of the wheels;

λр - coefficient of tangential elasticity of the front wheel;

λz is the coefficient of tangential elasticity of the rear wheel;

M is the total torque.

Now we find the torques acting on the wheels:

Mr - torque acting on the front wheel;

Mz is the torque acting on the rear wheel.

The figure 5 presents graphs of the possible dependencies of the torques acting on the wheels, on the angle of rotation of the front wheels. They illustrate the phenomenon of “power circulation”. Let us find such an increment of angular velocity, having informed that it will be possible to equalize the torques acting on different wheels, finding before this an increment to the rolling radii:

rr is the correction value of the rolling radii;

Δω is the value of the correction of the angular velocities of the wheels.

Now we will correct the torques acting on the wheels:

The figure 5 presents graphs of the adjusted torques acting on different wheels. It follows from them that the phenomenon of “power circulation” is completely eliminated.

The principle of controlling the torque on individual wheels for a fully blocked transmission will be considered using steady-state linear motion of a vehicle as an example, when the translational speeds of the axles of all the wheels are equal to each other and equal to the translational speed of the vehicle V _tf. If there is no sliding of the wheels and the wheels rotate at different angular speeds due to unequal gear ratios of individual variators, then the equality of speeds noted above can be ensured only due to circumferential deformations of the wheels that occur under the action of torques and corresponding changes in their radii. Therefore, when considering a locked transmission, in contrast to a fully differential transmission, it is necessary to take into account the dependence of the rolling radius of the wheel on the torque supplied to it

- радиусы качения колес в ведомом режиме и действительные радиусы качения колес;Where

- the rolling radii of the wheels in slave mode and the actual rolling radii of the wheels;

M _i - wheel torques;

λ _i - coefficients of change of the rolling radius from the torque;

n is the number of axes.

At the same time, the rolling radii of the wheels are related to the translational speed of the vehicle by the equation

where u _three - the total gear ratio of the i-th branch of the transmission, transmitting torque from the engine to the i-th wheel;

u _Tr - the same for all transmission branches, a common factor equal to the product of the gear ratio of all units of an arbitrary transmission branch with the exception of the variator.

If we now neglect the losses in the transmission, then from equations (2) and (3) by means of simple algebraic transformations, an expression can be obtained to determine the moment on the i-th wheel depending on the gear ratio of the i-th variator with rectilinear steady-state movement of the vehicle with a blocked transmission.

An analysis of equation (4) shows that to increase the torque on the i-th wheel, it is necessary to increase (decrease) the gear ratio of the i-th variator.

The figure 1 shows the continuously variable transmission of the vehicle and its control system, and Figures 2, 3, 4 schematically show possible schemes of the redistribution of torque between the vehicle propulsion, where:

1 - power plant with an electronic control unit;

2 - unit, allowing to break, transform and divert part of the power flow from the transmission;

3 - transfer case, which includes differentials with their locking devices and a reverse gear;

4 - interaxle differential (blocked);

5 - a through-gear central gearbox with an interwheel differential and a device for its remote locking;

6 - safety clutch;

7 - variator with a flexible metal element;

8 - additional gear;

9 - wheel gear;

10 - cardan or other gear capable of transmitting rotational motion at a distance;

11 - electronic transmission control unit;

12 - a sensor that determines the position of the fuel pedal;

13 - a sensor for measuring the angle of rotation of the steering wheel;

14 - sensor for measuring engine speed;

15 - sensor measuring the speed of the propulsion;

16 - a sensor for measuring the speed of the drive pulley of the variator;

17 - torque measurement sensor;

18 - sensors of longitudinal and transverse accelerations of the vehicle;

19 - switch of driving modes;

20 - mover;

21 is a device for changing the radius of the run-in of the variator pulleys.

The method for controlling a continuously variable transmission of a vehicle described in this application is not the only possible way to implement the claimed invention and achieve the above technical result and does not exclude other methods containing a combination of features included in an independent claim.

Claims (1)

A method for controlling a vehicle’s transmission by changing the speed ratios and distributing the ratios of the torques across various branches of the power transmission flows of a transmission having a power unit with an electronic control unit for it, an assembly that allows you to break, transform and divert part of the power flow from the transmission, motion mode switch, transfer case , electronic transmission control unit, cardan or other gears capable of transmitting rotational motion at a distance interconnecting transmission units, variators with flexible metal elements and devices for changing the radius of the run-in of variator pulleys, sensors for measuring the speed of the drive pulleys of variators, a sensor for measuring the frequency of rotation of the output shaft of a power plant, center differential, a sensor for positioning the fuel pedal, propulsors the fact that they carry out an individual change in the speed ratio and distribution of torques between the individual propulsion devices of the vehicle, while the transfer case transmits torque from the power unit to the transmission modules, and if the transmission has more than one drive axle, the transfer case can have one or more steps, which may include differentials with their locking devices, reversible gearboxes, mechanisms power take-offs, sensors that record transfer box operating modes, differentials, mechanisms that control transfer box operating modes, two or more movers d, and each transmission module consists of a central passage reducer with a differential and a device for remote locking of this differential, two safety couplings, two variators with metal flexible elements with devices for changing the rolling radius of the driving pulleys, two additional gearboxes, two half shafts, two wheel gears, two torque measurement sensors located between the central gear and the propulsion device, two speed sensors of the drive variator pulley, position married in front of the drive pulley of the variator, and two sensors of the frequency of rotation of the mover, and the torque is supplied to the input shaft of the central gearbox, where the leading elements of the safety clutch are connected to each of the two output shafts of the latter, and the drive pulleys of the variators are installed on their driven elements, and the driven pulleys CVTs transmit torque through additional gearboxes to wheel gearboxes via half shafts, then to propulsors, and the change in the radius of the run-in of each variator pulley is set electronically m transmission control unit, processing the signal from the position sensor fuel pedal, a torque measuring sensor, sensors of the engine speed and the vehicle wheel speed sensors variator drive pulleys, sensors longitudinal and transverse vehicle acceleration sensor measuring the steering angle.

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