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EP-4739551-A1 - A METHOD FOR DETERMINING A TORQUE TRANSFER BETWEEN WHEELS OF THE SAME AXLE IN LOW SPEED CONDITIONS

EP4739551A1EP 4739551 A1EP4739551 A1EP 4739551A1EP-4739551-A1

Abstract

There is described a method for determining a torque transfer between wheels of the same axle of a motor vehicle, comprising: - acquiring, for each wheel of the axle, at least one of a value of the internal pressure of a tyre of the wheel (TP_FR, TP_FL, TP_RR, TP_RL) and a value of travel of a suspension associated with the wheel (ST_FR, ST_FR, ST_RR, ST_RL), - determining, on the basis of said at least one of a value of an internal pressure of a tyre of the wheel (TP_FR, TP_FL, TP_RR, TP_RL) and a value of travel of a suspension associated with the wheel (ST_FR, ST_FR, ST_RR, ST_RL), a value of load acting on each wheel of the axle, - determining a difference between the values of the loads acting on the wheels of the axle (D24R, D24F), and - determining a value of a locking torque for the axle (32R, 32F) as a function of said difference between the values of the loads acting on the wheels of the axle.

Inventors

  • SALVO, Emanuele
  • GAVELLI, Marco

Assignees

  • Stellantis Europe S.p.A.

Dates

Publication Date
20260513
Application Date
20240703

Claims (8)

  1. 1. A method for determining a torque transfer between wheels of the same axle of a motor vehicle, comprising - acquiring, for each wheel of the axle, at least one of a value of the internal pressure of a tyre of the wheel (TP_FR, TP_FL, TP_RR, TP_RL) and a value of travel of a suspension associated with the wheel (ST_FR, ST_RR, ST_RL) , - determining, on the basis of said at least one of a value of an internal pressure of a tyre of the wheel (TP_FR, TP_FL, TP_RR, TP_RL) and a value of travel of a suspension associated with the wheel (ST_FR, ST_FR, ST_RR, ST_RL) , a value of load acting on each wheel of the axle, - determining a difference between the values of the loads acting on the wheels of the axle (D24R, D24F) , and - determining a value of a locking torque for the axle (32R, 32F) as a function of said difference between the values of the loads acting on the wheels of the axle.
  2. 2. The method according to claim 1, comprising acquiring, for each wheel of the axle, the value of the internal pressure of a tyre of the wheel TP_FR, TP_FL, TP_RR, TP_RL) and the value of the excursion of a suspension associated with the wheel (ST_FR, ST_FR, ST_RR, ST_RL) .
  3. 3. The method according to claim 1 or claim 2, wherein said load value acting on each wheel of the axle is a vertical load value.
  4. 4. The method of any one of the preceding claims, comprising determining a value of a locking torque for the axle (32R, 32F) as a function of said difference between said values of the loads acting on the wheels of the axle and a target torque for the axle (20F, 20R) .
  5. 5. The method according to claim 4, wherein said determining the value of the locking torque for the axle (32R, 32F) comprises determining a zero value of said locking torque when a torque value transmissible by the axle wheel subjected to the lower load exceeds 50% of the target torque value for the axle.
  6. 6. The method according to any one of the preceding claims, comprising defining an enabling condition for applying a locking torque for each axle (18F, 18R) , wherein said determining a value of the locking torque for the axle (32R, 32F) as a function of said difference between the values of the loads acting on the wheels of the axle comprises assigning a predetermined value to the locking torque if the enabling condition is not met.
  7. 7. The method according to claim 6, wherein said predetermined value is 0 Nm.
  8. 8. The method according to any one of the preceding claims, wherein the value of the load acting on each wheel of the axle is determined on the basis of said at least one of the value of the internal pressure of a tyre of the wheel (TP_FR, TP_FL, TP_RR, TP_RL) and a value of travel of a suspension associated with the wheel (ST_FR, ST_RR, ST_RL) by means of one-dimensional maps (LUT_L, LUT_R, LUT_DP) .

Description

A method for determining a torque transfer between wheels of the same axle in low speed conditions TEXT OF THE DESCRIPTION Field of the Invention The present invention refers to electronic systems for a variable torque distribution in motor vehicles. Known Art The variable torque distribution in the driveline of a motor vehicle (so-called "torque vectoring") is a significant part of the control strategies available on board a vehicle, and it may concern either the needs of a single axle - i.e., a variable distribution from right to left in the same axle - or the needs of a four-wheel drive, wherein the distribution may also vary between different axles. The present invention concerns the distribution within a single axle. The torque vectoring may be performed either by purely mechanical devices (typically, limited slip differentials which in case may be locked) , or by means of electronically controlled devices, which are the concern of the present invention. The latter type includes electronically controlled differentials (electronic limited slip differential or self-locking differential) , conventional friction brakes, as well as electric drive motors. More specifically, the existing strategies for torque vectoring generate commands to differentials and/or friction brakes which are based on vehicle accelerations measured by on-board sensors, according to an estimate of the wheels grip and to the speed of the wheels . At high vehicle speeds it is possible to control such devices in pre-emptively, with the purpose of correcting the vehicle trajectory or modifying the propensity to oversteer or understeer. On the other hand, at low vehicle speeds, especially in extreme off-road conditions (such as, e.g., in a so-called rock crawling drive) , the torque vectoring strategy has the only aim of maximizing the traction on the wheels having high grip. In such circumstances, the accelerations of the vehicle mainly represent the inclination of the vehicle, and therefore the control is mainly reactive: when a significant difference in speed is detected between the left wheel and the right wheel, the devices are controlled in such a way that both wheels have the same speed, and therefore the amount of torque necessary to propel the vehicle is sent to the wheel having the maximum grip. The reactive operation, however, implies the introduction of delays in the driveline, because it requires the occurrence of an initial slip event of the wheels on the individual axle, and therefore requires a difference in speed of the wheels. This leads to a temporary absence of propulsion from the whole axle, which is compensated only when the reactive control logic starts acting in order to limit the difference in speed between the wheels, and therefore only when a difference in speed is detected between the wheels of the axle. Obviously, this is all but desirable in a low-speed manoeuvre, because it can lead to unacceptably long intervention times. Object of the Invention The present invention aims at solving the technical problems outlined in the foregoing. Specifically, the invention aims at providing a method for the pre-emptive determination of a torque transfer between the wheels of an axle at low speeds of the vehicle, and therefore for a determination before the event which requires the torque transfer. Summary of the Invention The obj ect of the invention is achieved by means of a method having the features provided in the claims that follow, which form an integral part of the technical disclosure provided herein with reference to the invention . Brief Description of the Figures The invention will now be described with reference to the annexed Figures , provided as non-limiting examples only, wherein : - Figure 1 shows an exemplary block diagram of a method according to the invention; Figures 2 and 3 show exemplary block diagrams of elements of the method of the diagram as per Figure 1 , and Figure 4 shows an exemplary block diagram of an integration of a processing unit , implementing the method according to the invention, within the vehicle . The text matter provided in the Figures in addition to the references aims at supporting the description, without necessarily constituting a limitation thereof . Detailed Description Reference 1 in Figure 1 generally denotes a block diagram of a method for determining a torque trans fer between wheels of a same axle of a motor vehicle according to the invention . As a general introduction, and anticipating the detailed description of the individual steps which will be provided in the following, the method according to the invention comprises , in the embodiments thereof : - acquiring, for each wheel of the axle , at least one of a value of the internal pressure of a tyre of the wheel ( i . e . an inflation pressure ) and a value of travel of a suspension associated with the wheel , - determining, on the basis of said at least one of a value of an internal pressure of a tyre of t