Method for controlling the state of a drive train of a power train of an electric, hybrid or combustion engine vehicle

Abstract

A method for controlling a state of a drive train of a power train including at least one motive power source and a set of couplers and reducers of which respective engagements define a plurality of states of the drive train, by engagement of one or a plurality of energy sources in provision of torque and by the ratio of transmission of same to wheels. States targeted from a current state are ranked in real time on the basis of the difference between the motive force available in a current state and in each target state.

Claims

1. A method comprising: controlling a state of a drive chain of a power train having at least one motive power source, and a set of couplers and reducers of which respective engagements define a plurality of drive chain states, by engaging one or a plurality of energy sources providing torque and by a transmission ratio thereof to wheels; and ranking in real time drive chain states targeted from a current state on the basis of the difference between motive force available in the current state and in each target state, wherein the controlling of the state of the drive chain is based on the ranking of the drive chain states.

2. The control method as claimed in claim 1, wherein, in each of the drive chain states, a maximum motive force is defined on the basis of gear ratios, maximum torques that can be provided by an electric machine and a combustion engine, and on an engine speed or speed of a vehicle.

3. The control method as claimed in claim 1, wherein the target states are ranked as rising or descending depending on whether an available motive force difference compared with the current state is positive or negative.

4. The control method as claimed in claim 3, wherein the ranking of the target states is implemented in real time on the basis of a speed of movement of a vehicle.

5. The control method as claimed in claim 3, wherein if the difference in motive force between the targeted state and the current state is greater than a first calibrated threshold, the targeted state is considered to be rising compared with the current state.

6. The control method as claimed in claim 5, wherein if the difference in motive force between the targeted state and the current state is less than a second calibrated threshold, the targeted state is considered to be descending compared with the current state.

7. The control method as claimed in claim 6, wherein if the difference is strictly greater than the second threshold and strictly lower than the first threshold, a targeted state previously considered as a descending state remains a descending state and a targeted state previously considered as a rising state remains rising.

8. The control method as claimed in claim 1, wherein the ranking of the targeted states determines, in real time, a minimum level of motive force available in each targeted state to be able to be adopted as a current state.

9. The control method as claimed in claim 5, wherein a level of minimum force for a rising targeted ratio is greater than a level of minimum force for a descending targeted ratio.

Description

(1) The present invention will be better understood upon reading the following description of a non-limiting embodiment thereof, given with reference to the accompanying drawings, in which:

(2) FIG. 1 is a flowchart of the proposed strategy for ranking rising and regressing drive chain states, and

(3) FIG. 2 shows the force available to the wheel, for each state of the kinematic chain, on the basis of the speed.

(4) As indicated above, the ranking of the drive chain states established for the gearbox ratios of a combustion vehicle is ineffective in the case of a hybrid PT due to different possible combinations of wheel torque sources and transmission ratios. The strategy proposed is based on all traction forces available in each of the drive chain states available in a PT and on the corresponding vehicle architecture. Similarly to conventional transmissions, the term rising applies to a target state of a hybrid PT when this state provides the wheel with a tractive force that is less than that of the current ratio. Similarly, the term regressing or descending applies to a target drive chain state that provides the wheel with a greater tractive force compared with that of the current ratio.

(5) The flowchart of FIG. 1 shows the strategy. The first step is the calculation of the difference between the tractive force available at the wheel in the current state and the tractive force available at the wheel in a kinematic chain state selected as target. Three cases are shown: If this difference is greater than or equal to a first calibrated threshold, referred to as threshold_rising, the targeted state is considered to be a rising state compared with the current state. If this difference is less than or equal to a second calibrated threshold, referred to as threshold_regressing, the targeted state is considered to be a descending or regressing state compared with the current state. If the different is strictly greater than the threshold_regressing and strictly lower than the threshold_rising, two assessments are possible: a. if the targeted state was previously considered to be a regressing state then it remains regressing, b. if the target kinematic chain state was previously considered to be a rising state then the state remains rising.

(6) This strategy is applicable to all hybrid or combustion architectures, in particular to hybrid transmissions including a combustion engine and an electric machine, such as that described in publication WO2012/131259, comprising two main concentric shafts each carrying at least one downshifting pinion gear on a secondary shaft connected to the wheels of the vehicle. This transmission comprises two coupling means. The first may occupy at least three positions, in which: the combustion engine is decoupled from the kinematic chain connecting the electric machine to the wheels, the combustion engine drives the wheels with or without the addition of the electric machine in a long ratio, and the combustion engine and the electric machine are coupled so as to add together their respective torques in the direction of the wheels.

(7) The second coupling means may also occupy three positions, i.e. a neutral gear position and two ratio engagement positions (short and intermediate).

(8) This transmission has three ratios and seven kinematic chain states, for each of which FIG. 2 shows the available forces (maximum tractive force Fmax trs), on the basis of the speed of the vehicle. The two first ratios, short and intermediate, are accessible in electric mode. They define the two states ZEV1 and ZEV2. The third ratio, or long ratio, is accessible in combustion mode. It defines a state ICE3. Four hybrid states are accessible depending on the positions of the two coupling means: a first hybrid state HY1/1, in which the two main shafts are coupled and in which the torque descends over the short ratio, a second hybrid state HY2/2, in which the two main shafts are coupled and in which the torque descends over the intermediate ratio, a third hybrid state HY3/1, in which the two primary shafts are decoupled and in which the torque of the combustion engine descends over the long ratio and the torque of the electric motor descends over the short ratio, and a fourth hybrid state HY3/2, in which the two primary shafts are decoupled and in which the torque of the combustion engine descends over the long ratio and the torque of the electric motor descends over the intermediate ratio. In each of these states the maximum force is defined on the basis of the associated gear ratios, maximum torques that can be provided by the electric machine and the combustion engine, and also engine speed or speed of the vehicle. The targeted states are ranked as rising or descending depending on whether the available motive force difference is positive or negative. The table below illustrates the ranking of the target states of the drive chain on the basis of the current state HY31, depending on the speed of the vehicle, assuming that the previous state was HY32 and that this state was previously deemed to be rising (HY32 Rising) or descending (HY32 descending).

(9) TABLE-US-00001 F. HY31 F. HY32 Diff. HY32 HY32 V. veh (N) (N) (N) prev. target Force constraint (a) 30 5200 4200 1000 Rising Rising C1 (b) 50 4200 4190 10 Rising Rising C1 (c) 55 4000 4200 200 Rising Regressing C2 (d) 70 2000 3500 1500 Regressing Regressing C2 (e) 49 4210 4200 10 Regressing Regressing C2 (f) 45 4400 4200 200 Regressing Rising C1

(10) When the vehicle travels at 30 km/h and the current state HY31 has a force 1000 N greater than that available in the target state HY32, the latter, which was previously rising, remains rising (a).

(11) When the vehicle travels at 50 km/h and the current state HY31 has a force 10 N less than that available in the state HY32, the latter remains of the rising type however, because the difference is not sufficiently great to avoid hysteresis phenomena (b).

(12) When the vehicle travels at 55 km/h and the current state HY31 has a force 200 N less than that available in the state HY32, the latter then becomes of the regressing type (c).

(13) When the vehicle travels at 70 km/h and the current state HY31 has a force 1500 N less than that available in the state HY32, the latter remains of the regressing type (d).

(14) When the vehicle travels at 49 km/h and the current state HY31 has a force 10 N greater than that available in the state HY32, the latter remains of the regressing type, however, because the difference is not sufficiently great to change it without the appearance of hysteresis (e).

(15) When the vehicle travels at 45 km/h and the current state HY31 has a force 200 N greater than that available in the state HY32, the latter becomes of the rising type (f).

(16) In accordance with the method the ranking of all the targeted states is implemented in real time on the basis of the speed of movement of the vehicle and on the basis of the difference between the motive force available in the current state and in each target state.

(17) This ranking or typing of the target state (HY32 in the example above) also makes it possible to define, in real time, a minimum level or force constraint to be satisfied by this target state so as to be able to be adopted as a current ratio. Two constraint levels C1 or C2, depending on which the target state is rising or regressing, are defined in the table.

(18) The rising ratio constraint C1 is preferably greater than the regressing ratio constraint C2. The purpose of the distance between C1 and C2 is to impose a greater power reserve for the rising switches than for the descending switches so as not to choose a drive chain state that risks being abandoned in the event of a slight rise of the motive force setpoint.

(19) If the force available in the targeted state HY32 is less than the required constraint level (C1 or C2 for HY32), this state cannot be adopted. In cases (a), (b) and (f) the force available in state HY32 must be greater than the force constraint C1; in the other cases (c), (d) and (f) it is sufficient that this force is greater than the constraint C2 in order for the state HY32 to be adoptable.

(20) The ranking of the targeted states thus determines, in real time, a minimum level of motive force available in each targeted state so as to be able to be adopted as the current state. The minimum force level for a rising targeted ratio is greater than the minimum force level for a descending targeted ratio.

(21) This table shows how it is possible to control, in a particular case, the switches from one particular drive chain state, here HY31, to another state, HY32. With the proposed method this ranking is performed for all the possible changes between the states ICE 3, ZEV1, ZEV2, HY1/1, HY2/2, HY3/1, HY3/2. All of the switches between these states are thus controlled. This ranking is decisive for the choice of the optimal state of the drive chain.

(22) In the described example the PT has seven drive chain states, distributed over the three ratios of the transmission: a short and intermediate ratio in electric mode, a short ratio, an intermediate ratio and a long ratio in hybrid mode, and a long ratio in combustion mode. The method makes it possible to control all switches between the different states of the chain in electric mode, in hybrid mode and in combustion mode.

(23) This method, described on the basis of its application in the particular case of a hybrid transmission having the seven identified states, generally makes it possible to control the state of each drive chain of the power train comprising at least one motive energy source and a set of couplers and reducers of which the respective engagements define a plurality of accessible chain states, by the engagement of one or a plurality of energy sources in the provision of torque and by the transmission ratio thereof to the wheels.

(24) Generally, the method can be applied to any PT equipped with one or more energy sources usable with one or more transmission ratios, thus making it possible to control the switches between a number of states between the electric, hybrid and combustion modes.

(25) The method has numerous advantages. It firstly makes it possible to optimize the consumption and depollution of the vehicle. Because the electrification of a PT is primarily substantiated by the reduction in consumption, the strategy implemented may advantageously interact with the energy management laws thereof. The method also makes it possible to optimize the driving comfort of the vehicle by varying the level thereof, during operation, of the state of charge of the battery, and also the desired performance.