Method for controlling a hybrid transmission for a motor vehicle taking into account transition interruptions between kinematic modes

Abstract

A method controls a hybrid transmission for a motor vehicle that can operate according to at least two kinematic modes involving various connections of at least one internal combustion engine, at least one electric motor, and at least two drive wheels. The method includes controlling the transition between kinematic modes in accordance with the current kinematic mode during the start of the transition and a kinematic mode setting, if it is determined that the current kinematic mode is not equal to the kinematic mode of the transition and that the kinematic mode setting is not equal to the final kinematic mode, making a decision regarding the suitability of a transition interruption, during a change of request of the driver during which it is determined whether an interruption of the action is underway, and then continuing the transition or undertaking a new transition according to the result.

Claims

1. A method for controlling a hybrid transmission for a motor vehicle operable in at least two kinematic modes involving different connections of at least one internal combustion engine, of at least one electric machine, and at least two drive wheels, comprising: controlling a first transition between kinematic modes according to a current kinematic mode at an onset of the first transition and a kinematic mode setpoint, deciding, when it is determined that the kinematic mode setpoint has changed during the first transition, on whether an interruption of the first transition is possible, then, continuing the first transition or carrying out a second transition according to a result of the deciding on whether the interruption of the first transition is possible, and wherein the controlling the first transition between kinematic modes according to the current kinematic mode at the onset of the first transition and the kinematic mode setpoint includes: determining if the kinematic mode setpoint corresponds to the current kinematic mode, storing, when the kinematic mode setpoint does not correspond to the current kinematic mode, the current kinematic mode as an initial kinematic mode value and the kinematic mode setpoint as a final kinematic mode value, then determining a shift trajectory to pass a kinematic mode of the first transition from the initial kinematic mode to the final kinematic mode, then initializing a transition step counter to 1, then shifting the kinematic mode of the first transition according to the transition step counter, then determining if the current kinematic mode is equal to the kinematic mode of the first transition, determining, when the current kinematic mode is equal to the kinematic mode of the first transition, if the current kinematic mode is equal to the final kinematic mode, terminating, when the current kinematic mode is equal to the final kinematic mode, the control method, incrementing, when the current kinematic mode is not equal to the final kinematic mode, the transition step counter, then the control method continues to the shifting the kinematic mode of the first transition according to the transition step counter, determining, when the current kinematic mode is not equal to the kinematic mode of the first transition, if the kinematic mode setpoint is equal to the final kinematic mode, continuing, when the kinematic mode setpoint is equal to the final kinematic mode, the shifting the kinematic mode of the first transition according to the transition step counter.

2. The control method according to claim 1, in which the deciding on whether the interruption of the first transition is possible, during a change of request of a driver, includes the following: performing, when it is determined that the current kinematic mode is not equal to the kinematic mode of the transition and that the kinematic mode setpoint is not equal to the final kinematic mode, an analysis relating to the interruption decision, then determining whether or not to interrupt the first transition based on a result of the analysis.

3. The control method according to claim 2, in which, in order to continue the first transition or start the second transition according to an outcome of the deciding on whether the interruption of the first transition is possible, the following steps are performed: when it is determined that an action of the hybrid transmission is in the process of being interrupted, stopping the action, then determining if the kinematic mode setpoint corresponds to the current kinematic mode, or when it is determined not to interrupt the first transition, continuing the first transition toward the kinematic mode of the first transition according to the transition step counter, then determining if the current kinematic mode is equal to the kinematic mode of the first transition, and when the current kinematic mode is not equal to the kinematic mode of the first transition, continuing the first transition toward the kinematic mode of the first transition, and when the current kinematic mode is equal to the kinematic mode of the first transition, determining if the kinematic mode setpoint corresponds to the current kinematic mode.

4. The control method according to claim 2, in which changes between the kinematic modes are monitored to take place according to predefined shift trajectories.

5. The control method according to claim 4, in which the analysis relating to the interruption decision is based on a comparison of a cost of the predefined shift trajectories.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other features, objects and advantages of the invention will emerge on reading the following description, given only by way of non-limiting example, and with reference to the accompanying drawings in which:

(2) FIG. 1 illustrates a hybrid transmission for a motor vehicle,

(3) FIG. 2 illustrates the various kinematic modes of the transmission available depending on the positions of the dog clutches of the coupling systems,

(4) FIG. 3 is a simplified table of transitions taken from FIG. 2,

(5) FIG. 4 illustrates the main steps of transition control method allowing the kinematic mode change while taking interruptions into account, and

(6) FIG. 5 illustrates a method for monitoring kinematic mode transitions comprising transition interruptions.

DETAILED DESCRIPTION

(7) In FIGS. 2 and 3, the nine states E.sub.1 to E.sub.9 of the transmission of FIG. 1, and the 24 possible transitions a.sub.1 to a.sub.24 between these states are represented. Several paths are possible to move from one state to another. For example, to go from state E.sub.1 to state E.sub.7, the chains E.sub.1, a.sub.5, E.sub.4, a.sub.15, E.sub.7 or E.sub.1, a.sub.5, E.sub.4, a.sub.11, E.sub.5, a.sub.17, E.sub.8, a.sub.23, E.sub.7, etc. may be performed.

(8) To enable the decision, a cost (or weight) relative to each transition must be introduced in order to be able to determine how to satisfy the decision criteria selected.

(9) c.sub.i represents the cost associated with the a.sub.i transition.

(10) The total cost of a trajectory is thus the sum of the costs associated with the transitions covered within the scope of this trajectory. By repeating the second transition example described above, the following cost is obtained:
Cost(E.sub.1,a.sub.5,E.sub.4,a.sub.11,E.sub.5,a.sub.17,E.sub.8,a.sub.23,E.sub.7)=c.sub.5+c.sub.11+c.sub.17+c.sub.23

(11) The possibility of a transition interruption can thus be determined by comparing the cost of two trajectories: the one that would be followed, according to the programming tables, to loin the new destination, by returning to the initial kinematic mode (i.e. by renouncing the transition in progress), and the one that would be followed, according to the programming tables, to join the new destination, since the former destination (i.e. the transition in progress is completed before responding to the new destination).

(12) FIG. 4 illustrates a method for controlling the transmission making it possible to pass from a current kinematic mode to a kinematic mode setpoint. This method includes taking into account a transition interruption in the form of a kinematic mode setpoint change, in the course of transition.

(13) The method comprises three large sets of steps for controlling the transition between kinematic modes, to make a decision on whether a transition interruption, during a change request of the driver, then continue the transition or begin a new transition depending on the outcome of the decision.

(14) Steps 17 to 25 are used to control the transition between kinematic modes.

(15) Steps 26 and 27 are used to make a decision on the possibility of a transition interruption, during a change request of the driver.

(16) Steps 28 to 30 are used to continue the transition or to begin a new transition depending on the outcome of the decision.

(17) During a first step 17, it is determined if the kinematic mode setpoint corresponds to the current kinematic mode. If this is the case, the method is terminated.

(18) If this is not the case, the method continues during a second step 18, during which the current kinematic mode is stored in an initial kinematic mode value and the kinematic mode setpoint in a final kinematic mode value.

(19) During a step 19, the trajectory (defined for example by a succession of peaks E.sub.i=kin_mod (i)) is determined to pass from the initial kinematic mode to the final kinematic mode.

(20) During a step 20, the transition step counter is reset to 1.

(21) The process continues with a step 21 during which the mode transition is commanded to the kinematic mode of the kin_mod(i) transition step.

(22) At a step 22, it is determined if the current kinematic mode is equal to the kinematic mode of the intermediate transition step.

(23) If this is the case, the method continues to a step 23, during which it is determined if the current kinematic mode is equal to the final kinematic mode. If this is the case, the method is terminated. If this is not the case, the transition step counter is incremented to step 24 before the method continues to step 21.

(24) If it is determined in step 22, that the current kinematic mode is not equal to the kinematic mode of the kin_mod (i) transition step, the method continues to step 25 during which it is determined if the kinematic mode setpoint is equal to the final kinematic mode.

(25) If this is the case, the method continues to step 21. If this is not the case, the method continues to step 26, during which the stress relating to the interruption decision described above in step 27 is performed, it is determined if an interruption of the action is preferable.

(26) The conditions to declare that it is preferable to interrupt the action are as follows:

(27) No irremediable action is initiated (e.g.: the dog clutch system is not yet in motion), and

(28) The cost analysis favors the interruption in relation to continuing the current action.

(29) If, at step 27, it was determined that there is an interruption of the current action, the method continues to step 28, during which the stopping of the current action is commanded at the transmission level followed by resumption of the method at step 17.

(30) If, at step 27, it was determined that current action is not interrupted, the method continues to step 29 during which the transition continues to the kinematic mode of the intermediate transition step.

(31) The process then continues to step 30 during which it is determined if the current kinematic mode is equal to the kinematic mode of the targeted intermediate transition step. If this is not the case, the method continues to step 29. If this is the case, the method continues to step 17.

(32) FIG. 5 illustrates the monitoring method including management of transition interruptions.

(33) In relation to FIG. 3, the following elements were added to the stable states (i.e. established kinematic modes) E.sub.1 to E.sub.9, and to the transitions a.sub.1 to a.sub.24:

(34) T.sub.i-j: the state allowing the control of the transition from state E.sub.i to state E.sub.j iT.sub.i-j: the flag for interrupting the transition T.sub.i-j to allow a return to state E.sub.i via transition T.sub.j-i.

(35) In the method illustrated by FIG. 5, the decision-making mechanism makes it possible to assess the flags iT.sub.i-j. As such, if the decision to interrupt the current transition is made (i.e. iT.sub.i-j=1), the transition T.sub.i-j (that was initiated) passes to transition T.sub.j-i which makes it possible to return to state E.sub.i. The kinematic mode changes are thus monitored to take place according to predefined shift trajectories. This monitoring makes is possible to interrupt an ongoing action so that the driver's intentions can be better taken into account. Finally, as indicated above, the decision-making mechanism is based on a comparison of the cost of the trajectories.