Method for validating at least one combination of transmission ratios

Abstract

The invention relates to validation, applied to a powertrain (20) of an electric or hybrid motor vehicle (10) comprising two traction members (41, 42, 43) and a gearbox (51, 52) adapted to provide several combinations of transmission ratios between the traction members and at least one output shaft (71, 72) of the gearbox, of a combination of transmission ratios, the method comprising the following steps: - acquisition of an intrinsic maximum rotation speed of each member; - calculation, for each member, on the basis of said combination of transmission ratios and the intrinsic maximum rotation speed of said member, of an upper rotation limit relating to an output shaft driven by said member; - acquisition of an instantaneous rotation speed of a first of the members;- calculation, on the basis of said combination of transmission ratios and the instantaneous rotation speed, of a current rotation speed relative to the output shaft driven by said first member; - validation or not of the combination of transmission ratios on the basis of a comparison between an upper rotation limit and said current rotation speed. Figure for the abstract: Fig. 1;

Description

Title of the invention: Method for validating at least one combination of transmission ratios Technical field of the invention

[0001] The present invention generally relates to the control of a powertrain of an electric or hybrid motor vehicle.

[0002] It relates more particularly to a method for validating at least one combination of transmission ratios.

[0003] It also relates to an electric or hybrid motor vehicle whose powertrain is controlled according to this method.

[0004] The invention finds a particularly advantageous application in the determination of transmission ratio changes. State of the art

[0005] An electric or hybrid motor vehicle comprises a powertrain which may comprise at least two traction members, for example a heat engine and an electric machine, and a gearbox. It also comprises an electronic unit adapted to control the vehicle's powertrain. Indeed, this powertrain can conventionally be controlled according to several combinations of transmission ratios. A transmission ratio defines, for each member, whether this member supplies power to the drive wheels and, if so, what is the multiplication coefficient (reduction or demultiplication) between the primary shaft fixed to the rotating part of the traction member and the output shaft of the gearbox which drives the wheels. A transmission ratio thus defines a kinematic state of the powertrain.

[0006] The traction components of the powertrain, however, have one or more operating limits, in particular a maximum rotation speed above which the components are in an overspeed situation, which implies mechanical risks which can lead to breakage of the traction components used. Electric machines mainly have a maximum limit while thermal engines have a maximum limit and a minimum limit.

[0007] Different strategies ensure that the mechanical limits of the traction components are not exceeded. Conventionally, the limits of the components are expressed in a longitudinal speed of the vehicle (for example in km / h) so that they can be compared with the instantaneous longitudinal speed of the vehicle. The latter, which represents the current speed of the vehicle, is typically given by the vehicle stability control (VDC for “Vehicle Dynamic Control”).

[0008] This approach therefore requires knowledge of numerous technical characteristics of the vehicle, such as the size of the wheels and the thickness diameter of the tires, in order to convert the rotation speeds of the components into longitudinal speeds.

[0009] Thus, this approach is complex to implement and needs to be adjusted for each vehicle. It is also not very precise on the one hand because of the difficulty of estimating certain characteristics of the vehicle such as the thickness of the tires (which depends on the inflation), and on the other hand because the current speed, used for comparison with the limits, is acquired by means of a vehicle system which is not dedicated to the control of the powertrain. In addition, the calculation may be distorted in conditions of low wheel grip (slippage) on the roadway since the rotation speed of the wheels is no longer proportional to the longitudinal speed of the vehicle. Presentation of the invention

[0010] In this context, the present invention proposes a validation method, applied to a powertrain of an electric or hybrid motor vehicle comprising at least two traction members and at least one gearbox adapted to ensure several combinations of transmission ratios between the traction members and at least one output shaft of the gearbox, of at least one combination of transmission ratios, the method comprising the following steps: - acquisition of an intrinsic maximum rotation speed of each organ; - calculation, for each member, on the basis of said combination of transmission ratios and the intrinsic maximum rotation speed of said member, of an upper rotation limit relative to an output shaft driven by said member; - acquisition of an instantaneous rotation speed of a first of the organs; - calculation, on the basis of said combination of transmission ratios and the instantaneous rotation speed, of a current rotation speed relative to the output shaft driven by said first member; - validation or not of the combination of transmission ratios on the basis of a comparison between one of said upper rotation limits and said current rotation speed.

[0011] For the purposes of the invention, “validating” a combination means giving an indication, for example represented by a Boolean, allowing an electronic unit responsible for controlling the gearbox, such as the vehicle’s computer, to authorize the combination (the powertrain can then be controlled according to this combination) or on the contrary to reject the combination (the powertrain should then not be controlled according to this combination). When the combination studied is the current combination, i.e. the one according to which the powertrain is being controlled, the rejection of the combination therefore indicates to the electronic unit that it is time to change the combination.

[0012] Thus, the invention proposes to express in rotational speeds both the limits of the traction members and the current speed of the vehicle. By working only with rotational speeds, a common reference is adopted for the limits of the traction members and the current speed of the vehicle, which allows comparisons of exceeding the limits to be carried out simply. In other words, the rotational speeds relative to the output shafts, driven by the members, then represent standardized speeds which are comparable with each other.

[0013] It is therefore no longer necessary to convert the maximum rotational speeds of the traction members into longitudinal speed of the vehicle and therefore to know precisely the characteristics of the vehicle such as the diameter of the wheels.

[0014] Furthermore, the current speed of the vehicle is determined directly by means of the instantaneous rotational speed(s) of the components. Thus, the current speed is known very precisely. It is also directly expressed in the same system of units (for example in revolutions per minute) as the limits of the components.

[0015] Finally, the conditions of low wheel adhesion are correctly taken into account since the calculation is based on the output shaft driving the wheels whose rotation speed is, in all cases, proportional to that of the wheels.

[0016] Other advantageous and non-limiting characteristics of the method according to the invention, taken individually or in all technically possible combinations, are the following: - said one of said upper rotation limits used for the comparison is the lowest upper rotation limit among the upper rotation limits of the at least two members; - it is planned: the acquisition of the instantaneous rotation speed of each organ, the calculation of a current rotation speed for each organ, and the current rotation speed used for the comparison is the highest current rotation speed among the current rotation speeds of the at least two organs; - the calculation of the upper rotation limit is based on a ratio, which depends on said combination of transmission ratios, between: the rotation of said member, and the rotation of the output shaft driven by said member or the rotation of the wheels driven by said member; - the calculation of the current rotation speed is based on a ratio, which depends on said combination of transmission ratios, between: the rotation of said first member, and the rotation of the output shaft driven by said first member or the rotation of wheels driven by said member; - it is planned to calculate, for each organ, an anticipated limit, relative to the output shaft driven by said organ, which is lower than the upper rotation limit, and the comparison is made between one of said anticipated rotation limits and said current rotation speed; - it is planned, for each organ, to calculate the anticipated rotation limit on the basis of a temporal variation of the instantaneous rotation speed of said organ; - it is planned to acquire an intrinsic minimum rotation speed of at least one of the members and to calculate, for said member, a lower rotation limit relative to the output shaft driven by said member, and the validation or not of the combination of transmission ratios is also based on a comparison between said lower rotation limit and said current rotation speed; - said combination of transmission ratios, validated or not, is the combination which is currently used to drive the wheels of the vehicle; - it is planned: to calculate for each member an upper rotation limit for each combination of transmission ratios, to calculate a current rotation speed for each combination of transmission ratios, to validate or not each combination of transmission ratios, each validation or not of a combination of transmission ratios being based on a comparison between one of said upper rotation limits and said current rotation speed which are associated with said combination of transmission ratios.

[0017] The invention also proposes an electric or hybrid motor vehicle comprising: - a powertrain which comprises at least two traction members and a gearbox adapted to provide several combinations of transmission ratios between the traction members and at least one output shaft; - a computer programmed to implement a method for validating a combination of transmission ratios for controlling the powertrain according to a method as described above.

[0018] Of course, the various features, variants and embodiments of the invention may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive. Detailed description of the invention

[0019] The description which follows with reference to the appended drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be implemented.

[0020] In the attached drawings:

[0021] [Fig-1] is a schematic representation seen from above of a vehicle according to the invention.

[0022] [Fig.2] is a block diagram of a sequence of steps for implementing a method for validating a combination of transmission ratios according to the invention.

[0023] An electric or hybrid motor vehicle 10 according to the invention is shown in [Fig.l]. The vehicle 10 comprises a powertrain 20 intended to move the vehicle 10 forward. In the example shown in [Fig.l], the powertrain 20 comprises in particular three traction members (hereinafter called members) which make it possible to drive the wheels 31, 32 of the vehicle 11. The powertrain 20 here comprises: - a thermal engine 41, here connected to the front wheels 31; - a front electric machine 42, here also connected to the front wheels 31; - a rear electric machine 43, connected to the rear wheels 32.

[0024] In order to mechanically connect the members 41, 42, 43 to the wheels 31, 32, the powertrain 20 also comprises a front gearbox 51 and a rear gearbox 52.

[0025] The front gearbox 51 is connected, at the input, to a primary shaft 61 of the heat engine 41 and to a primary shaft 62 of the front electric machine 42. The primary shafts 61, 62 are connected to the rotating parts of the members 61, 62. Thus, the primary shaft 61 of the heat engine 41 is connected to the crankshaft of the latter and the primary shaft 62 of the front electric machine 42 is connected to the rotor of the latter. At the output, the front gearbox 51 is connected to a front output shaft 71 which drives, via a differential 80, two front axles 81, and by continuity the front wheels 31.

[0026] The front gearbox 51 has discrete multiplication ratios, i.e. reduction or demultiplication ratios, for the transmission between the primary shaft 61 of the thermal engine 41 and the front output shaft 71. Here, the front gearbox 51 has four discrete ratios. The front gearbox 51 also has discrete multiplication ratios, here two, for the transmission between the primary shaft 62 of the front electric machine 42 and the front output shaft 71.

[0027] Here, the front output shaft 71 drives the front wheels 31 with a fixed proportionality coefficient different from one, which means that one revolution of the front output shaft 71 does not correspond exactly to one revolution of the front wheels 31. This fixed proportionality coefficient is here applied by the differential 80. For example, taking into account the differential 80, the ratios numbered from one to four for the thermal engine 41 allow respectively, a reduction of 13.06, 6.27, 3.81 and 2.86; and the ratios numbered one and two for the front electric machine 42, allow respectively a reduction of 12.92 and 4.3.

[0028] Here, the front gearbox 51 is thus designed so that the primary shaft 61 of the thermal engine 41 and the primary shaft 62 of the front electric machine 42 can rotate at different rotational speeds. The front gearbox 51 is for example designed according to E-TECH technology.

[0029] The rear gearbox 52 is connected, at the input, to the primary shaft 63 of the rear electric machine 43. At the output, the rear gearbox 52 is connected to a rear output shaft 72 which drives a rear axle 82 and, by continuity, the rear wheels 32. The rear gearbox 52 has discrete ratios, for example two, for the transmission between the primary shaft 63 of the rear electric machine 43 and the rear output shaft 72. Here, the rear output shaft 72 drives the wheels with a fixed proportionality coefficient of one, which means that one revolution of the rear output shaft 72 corresponds exactly to one revolution of the rear wheels 32. Alternatively, a rear differential may be provided between the rear output shaft and the rear axles providing a fixed proportionality coefficient other than one.

[0030] The output shafts 71, 72 are thus here output shafts of the gearboxes 51, 52. The front output shaft 71 is driven by the thermal engine 41 or the front electric machine 42. The rear output shaft 72 is driven by the rear electric machine 43.

[0031] The motor vehicle 10 also comprises a computer 90 which is here programmed to control the powertrain 20 in the sense that it automatically determines the discrete ratios of each gearbox 51, 52. The gearboxes 51, 52 are thus here so-called “automatic” gearboxes, which means that the gear changes are not managed by the driver of the vehicle 10.

[0032] The computer 90 can control the powertrain 20 according to several combinations of transmission ratios between the members 41, 42, 43 and the output shafts 71, 72. Here, since the vehicle 10 comprises three members 41, 42, 43, each combination of transmission ratios is given by three values ​​each representing a discrete ratio associated with one of the members. These values ​​are here positive or zero integer values. For example, the combination of transmission ratios “2, 2, 1” means that the second gear (of the four) is engaged for the thermal engine 41, that the second gear (of the two) is engaged for the front electric machine 42 and that the first gear (of the two) is engaged for the rear electric machine. A zero value in a combination means that the member does not provide power for the traction or propulsion of the vehicle 10.Thus, for example, in the combination “1, 1, 0”, the rear electric machine 43 is not clutched and the other two members 41, 42 are in their respective first gear.

[0033] The computer 90 can control the powertrain 20 according to a predefined number of transmission ratio combinations. The transmission ratio combinations are simply called combinations hereinafter. The computer 90 only has certain combinations in memory here since several combinations are of little interest, such as a “4, 1, 1” combination with a very high ratio for the thermal engine and very low ratios for the motors electric. In other words, not all possible combinations are considered, but only those that make sense (one will almost never use the smallest gear for one component and the largest for another). Therefore, a pre-selection stage of possible combinations is planned during the design of the vehicle 10.

[0034] The computer 90 comprises at least one memory and at least one processor. Thanks to its memory, it stores data used in the context of the method described below. In particular, it stores a computer application, consisting of computer programs comprising instructions whose execution by the processor allows the computer 90 to implement the method described below. In other words, the processor is programmed to implement the method described below.

[0035] The computer 90 also comprises input interfaces adapted to receive input signals coming from different sensors on board the vehicle 10. Here, the input interfaces of the computer 13 allow it in particular to have access to the CAN data bus of the motor vehicle 10. In general, the computer 90 can acquire, thanks to its input interfaces, instantaneous rotation speeds of the members 41, 42, 43, that is to say the rotation speeds of the primary shafts 61, 62, 63 of the members 41, 42, 43.

[0036] The method according to the invention is illustrated in [Fig. 2]. This method makes it possible to validate at least one combination of transmission ratios, in particular the one according to which the powertrain 20 is being controlled. In the example of [Fig. 2], the computer 90 can control the powertrain 20 according to twenty combinations of transmission ratios. As will appear in detail below, the calculations are implemented for the twenty combinations of transmission ratios in parallel.

[0037] The steps of the method are here implemented repeatedly. The computer 90 is thus programmed to implement the method recursively, that is to say step by step, for example at a constant time step. A particular iteration of the method is described below.

[0038] The method begins with a first step of acquiring an intrinsic maximum rotation speed of each member 41, 42, 43. Each intrinsic maximum rotation speed depends on the design of the member 41, 42, 43 in question. This data is for example provided by the manufacturer of the members 41, 42, 43. Here, it is recorded in the memory of the computer 90. Acquiring it then means accessing the values ​​recorded in the memory. The first step thus makes it possible to define the intrinsic limit of each member 41, 42, 43.

[0039] As shown in [Fig.2], this step includes the acquisition of a maximum rotation speed V_MAX_1 of the thermal engine 41 (block 101), a maximum rotation speed V_MAX_2 of the front electric machine 42 (block 102) and a maximum rotation speed V_MAX_3 of the rear electric machine 43 (block 103). The maximum rotation speed V_MAX_1 of the thermal engine 41 is for example 6000 rpm and the maximum rotation speeds V_MAX_2, V_MAX_3 of the electric machines 42, 43 are 10,000 rpm.

[0040] Here, the first step also includes the acquisition of an intrinsic minimum rotation speed V_MIN_1 of the heat engine 41 (also at block 101). This minimum rotation speed V_MIN_1 makes it possible to avoid stalling of the heat engine 41. The electrical machines do not have an intrinsic minimum rotation speed. In other words, the intrinsic minimum rotation speeds of the electrical machines are equal to zero.

[0041] The method continues with a second step of calculating, for each member 41, 42, 43, an upper limit of rotation of the output shaft 71, 72 driven by said member 41, 42, 43. The second step here more specifically comprises the calculation of an upper limit of rotation for each member and for each combination.

[0042] In this second step, it is determined which speeds at the output shafts 71, 72 of the gearboxes 51, 52 can be supported by the members 41, 42, 43.

[0043] For this, the computer 90 has in memory, for each member 41, 42, 43 and for each combination, a ratio between the rotation speed of said member 41, 42, 43 and the rotation speed of the output shaft 71, 72 driven by said member 41, 42, 43. Each ratio here represents, for a given member and a given combination, the multiplication provided by the gearbox connected to the member, for the discrete ratio indicated by the combination. Each ratio is therefore here defined as the number of revolutions of the primary shaft corresponding to one revolution of the output shaft.

[0044] Alternatively, the ratios can take into account the fixed proportionality coefficients defined previously between the output shafts (front and rear) and the wheels. This then amounts to also taking into account the differential between the front axles (and the rear differential when present). Thus, for each component, the ratios can also be defined as the number of revolutions of the primary shaft corresponding to one revolution of the wheels driven by said component. For example, thus defined, the ratio of the thermal engine for the combination “1, 1, 0” would be 13.06 (which corresponds to the gear ratio described previously).

[0045] Here, the computer 90 therefore has in memory twenty ratios, referenced R_1 in [Fig.2], for the thermal engine 41 (which can take four values ​​representing the four discrete ratios), twenty ratios, referenced R_2 and R_3, for each electrical machine 42, 43 (which can take two values ​​representing the two discrete ratios).

[0046] As shown in [Fig.2], this second step includes the calculation of an upper rotation limit L_SUP_1 for the heat engine 41 (block 111). This upper rotation limit L_SUP_1 is here a vector of twenty values, each value being associated bijectively with one of the twenty combinations. Each value of this upper rotation limit L_SUP_1 is calculated by dividing the maximum rotation speed V_MAX_1 of the heat engine 41 by the ratio of the associated combination.

[0047] Similarly, the second step comprises calculating an upper rotation limit L_SUP_2 for the front electric machine 42 (block 112) and an upper rotation limit L_SUP_3 for the rear electric machine 43 (block 113). These upper rotation limits L_SUP_2, L_SUP_3 are also respectively vectors of twenty values, each value of a vector being associated bijectively with one of the twenty combinations, each value of a vector being calculated by dividing the maximum rotation speed V_MAX_2, V_MAX_3 by the ratio of the associated combination.

[0048] Here, the second step also includes the calculation of a lower rotation limit L_INF_1 for the heat engine 41 (also at block 111). This lower rotation limit L_INF_1 is also a vector of twenty values, each value being associated bijectively with one of the twenty combinations. Each value of this lower rotation limit L_INF_1 is calculated by dividing the minimum rotation speed V_MIN_1 of the heat engine 41 by the ratio of the associated combination.

[0049] The method then comprises a third step of acquiring an instantaneous rotation speed of each of the members 41, 42, 43.

[0050] Here, the computer 90 acquires, via the CAN data bus, the instantaneous rotation speed V_INS_1 of the primary shaft 61 of the thermal engine 41 (block 121), the instantaneous rotation speed V_INS_2 of the primary shaft 62 of the front electric machine 42 (block 122) and the instantaneous rotation speed V_INS_3 of the primary shaft 63 of the rear electric machine 43 (block 123).

[0051] The instantaneous rotation speeds V_INS_1, V_INS_2, V_INS_3 make it possible, on the one hand, in a fourth step of the method, to calculate a current rotation speed of the output shaft 71, 72 driven by each of the members 41, 42, 43. The fourth step here more specifically comprises the calculation of a current rotation speed for each member and for each combination.

[0052] The fourth step thus aims to determine the rotation speeds of the output shafts 71, 72 of each gearbox 51, 52 taking into account the rotation speed of each member 41, 42, 43.

[0053] As shown in [Fig.2], this fourth step comprises the calculation of a current rotation speed V_COU_1 for the heat engine 41 (block 131). This current rotation speed V_COU_1 is here a vector of twenty values, each value being associated bijectively with one of the twenty combinations. Each value of this current rotation speed V_COU_1 is calculated by dividing the instantaneous rotation speed V_INS_1 of the heat engine 41 by the ratio of the associated combination.

[0054] Similarly, the fourth step comprises the calculation of a current rotation speed V_COU_2 for the front electric machine 42 (block 132) and a current rotation speed V_COU_3 for the rear electric machine 43 (block 133). These current rotation speeds V_COU_2, V_COU_3 are also respectively vectors of twenty values, each value of a vector being associated bijectively with one of the twenty combinations, each value of a vector being calculated by dividing the instantaneous rotation speed V_INS_2, V_INS_3 by the ratio of the associated combination.

[0055] The instantaneous rotation speeds V_INS_1, V_INS_2, V_INS_3 also make it possible, in a fifth step, to calculate, for each member 41, 42, 43, an anticipated limit of the output shaft 71, 72 driven by said member 41, 42, 43. The fourth step here more specifically comprises the calculation of an anticipated limit for each member and for each combination.

[0056] Advantageously, the anticipated limits are more restrictive limits than the upper limits and the lower limit. They thus provide a safety margin by taking into account the temporal evolution of the current regime, that is to say the instantaneous rotational speeds. In other words, the anticipated limits make it possible to take into account an acceleration or a deceleration of the vehicle 10 so as not to authorize a combination which would be very quickly refused because of the variation in speed of the vehicle 10.

[0057] To do this, the computer 90 first estimates the temporal variation of the instantaneous rotation speed V_INS_1, V_INS_2, V_INS_3 of each member 41, 42, 43.

[0058] As shown in [Fig.2], the computer 90 calculates a derivative D_1 with respect to time of the instantaneous rotation speed V_INS_1 of the heat engine 41 (block 141). This derivative D_1 is here calculated discretely, for example over the last three or four time steps, that is to say on the basis of the last three or four instantaneous rotation speeds V_INS_1 of the heat engine 41 which have been acquired. Thus, the derivative D_1 is for example calculated as the difference between the instantaneous rotation speed V_INS_1 last acquired and the instantaneous rotation speed V_INS_1 acquired three time steps before, divided by the duration of the three time steps.

[0059] In the same way, the computer 90 calculates a derivative D_2 with respect to time of the instantaneous rotation speed V_INS_2 of the front electric machine 42 (block 142) and a derivative D_2 with respect to time of the instantaneous rotation speed V_INS_3 of the rear electric machine 43 (block 143).

[0060] During the first iteration of the method, the derivatives are here considered equal to zero. During the second iteration, the derivatives are for example calculated over two time steps, and so on until the instantaneous speeds over the three or four no time is available.

[0061] During this fifth step, the calculator 90 determines, for each member and for each combination, a reduction.

[0062] For this, the computer 90 has in memory, for each member 41, 42, 43 and for each combination, a reduction coefficient. The reduction coefficients are for example determined empirically during test sessions with the vehicle 10 equipped with the computer 90.

[0063] Here, the computer 90 therefore has in memory twenty reduction coefficients, referenced CR_1 in [Fig.2], for the thermal engine 41 (which can take four values ​​for the four discrete ratios), twenty reduction coefficients, referenced CR_2 and CR_3, for each electric machine 42, 43 (which can take two values ​​for the two discrete ratios).

[0064] As shown in [Fig.2], the computer 90 calculates a reduction RED_1 of the heat engine 41 (block 151). This reduction RED_1 is here a vector of twenty values, each value being associated bijectively with one of the twenty combinations. Each value of this reduction RED_1 is calculated by multiplying the derivative D_1 of the heat engine 41 by the reduction coefficient of the associated combination.

[0065] In the same way, the calculator 90 calculates a reduction RED_2 for the front electric machine 42 (block 152) and a reduction RED_3 for the rear electric machine 43 (block 153). These reductions RED_2, RED_3 are also respectively vectors of twenty values, each value of a vector being associated bijectively with one of the twenty combinations, each value of a vector being calculated by multiplying the derivative D_2, D_3 by the reduction coefficient of the associated combination.

[0066] Here, the fifth step also includes the calculation of an increase A_1 for the thermal engine 41 (also at block 151). For this, the computer 90 has in memory, for the thermal engine 41, for each combination, an increase coefficient. The increase coefficients are for example determined empirically during test sessions with the vehicle 10 equipped with the computer 90. The increase coefficients are for example between 10 and 500. The computer 90 therefore has in memory twenty increase coefficients, referenced CA_1 in [Fig.2] (which can take four values ​​for the four discrete ratios). The augmentation A_1 is also a vector of twenty values, each value being associated with one of the twenty combinations. Each value of this augmentation A_1 is calculated by multiplying the derivative D_1 of the heat engine 41 by the augmentation coefficient of the associated combination.

[0067] The fifth step finally includes the calculation of the anticipated limits of each member 41, 42, 43.

[0068] As shown in [Fig.2], the calculator 90 calculates an upper anticipated limit L_ANT_SUP_1 of the heat engine 41 by taking the difference, in vector form, between the upper rotation limit L_SUP_1 and the reduction RED_1 of the heat engine 41 (block 161). Each value of the upper anticipated limit L_ANT_SUP_1 is thus associated bijectively with one of the combinations and is defined as the difference between the upper rotation limit value L_SUP_1 and the reduction value RED_1 associated with said combination.

[0069] In the same way, the calculator 90 calculates an upper anticipated limit L_ANT_SUP_2 of the front electric machine 42 by taking the difference, in a vectorial manner, between the upper rotation limit L_SUP_2 and the reduction RED_2 of the front electric machine 42 (block 162). The calculator 90 also calculates an upper anticipated limit L_ANT_SUP_3 of the rear electric machine 43 by taking the difference, in a vectorial manner, between the upper rotation limit L_SUP_3 and the reduction RED_3 of the rear electric machine 43 (block 163).

[0070] Here, the calculator 90 also calculates a lower anticipated limit L_ANT_INF_1 of the heat engine 41 by summing, in vectorial fashion, the Lower rotation limit L_INF_1 and the increase A_1 of the heat engine 41 (also at block 161).

[0071] The method then comprises a sixth step of selection from among the upper anticipated limits and from among the current rotation speeds. The idea of ​​this sixth step is to associate each combination with one of the upper anticipated limits and one of the current rotation speeds in order to take into account the most critical case. In other words, for each combination, this amounts to determining which upper anticipated limit is most likely to be exceeded in order to subsequently reduce the validation to a single comparison (with regard to the upper anticipated limits).

[0072] During the sixth step, the computer 90 more particularly selects the upper anticipated limit L ANT SUP 1, L ANT SUP 2, L ANT SUP 3, the smallest among those of all the members 41, 42, 43 (block 200). It records the selected upper anticipated limit, here referenced L_ANT_SUP in [Fig.2], for the subsequent steps.

[0073] Here, this selection is made by taking into account the operating mode of the vehicle 10, referenced M in [Fig.2]. For example, when the vehicle 10 operates in a purely electric mode, the selection is made only from the upper anticipated limits L_ANT_SUP_2, L_ANT_SUP_3 of the electric machines 42, 43. When the vehicle 10 operates in a hybrid mode, the selection is made from all the upper anticipated limits L_ANT_SUP_1, L_ANT_SUP_2, L_ANT_SUP_3. Generally, if a member 41, 42, 43 does not participate in the traction of the vehicle 10 (in practice when it is not clutched), when the calculator 90 implements the sixth step, its upper anticipated limit is not taken into account for the selection.

[0074] Symmetrically, the computer 90 more particularly selects the current rotation speed V_COU_1, V_COU_2, V_COU_3 the greatest among those of all the members 41, 42, 43 (also at block 200). It records the selected current rotation speed, here referenced V_COU in [Fig.2], for the subsequent steps.

[0075] Here again, this selection is made by taking into account the operating mode M of the vehicle 10. If a member 41, 42, 43 does not participate in the traction of the vehicle 10 when the computer 90 implements the sixth step, its current rotation speed is not taken into account for the selection.

[0076] In the sixth step, the computer 90 also keeps in memory the lower anticipated limit L_ANT_INF_1 of the thermal engine 41 for the subsequent steps, which is therefore the selected lower anticipated limit. However, it does not keep it in memory if the operating mode M of the vehicle 10 indicates that the thermal engine 41 does not participate in traction (100% electric mode). In this case, the subsequent steps which depend on it (blocks 303 and 304) are not implemented. This amounts to considering that the selected lower anticipated limit that the computer keeps in memory is equal to zero.

[0077] The method then comprises a seventh step of comparing the current regime, represented by the current rotation speed selected in the sixth step, with the limits of the organs, represented by the upper anticipated limit and the lower anticipated limit selected in the sixth step.

[0078] The seventh step thus corresponds to testing the limits of the organs in relation to a current state of the vehicle, which subsequently allows decisions to be made on the combinations (in the seventh step).

[0079] As shown in [Fig.2], with regard to the upper limit, the computer 90 calculates the difference between the selected upper anticipated limit L_ANT_SUP and the selected current rotation speed V_COU (block 301). This difference is calculated in vector form. The result of this difference, called the upper difference and referenced DIF_SUP in [Fig.2], is therefore a vector, here of twenty values ​​for the twenty combinations, each value being associated bijectively with one of the combinations and being defined as the difference between the value of the selected upper anticipated limit L_ANT_SUP and the value of the current rotation speed V_COU which are associated with said combination.

[0080] The calculator 90 then compares the upper difference DIF_SUP to a vector of upper threshold values ​​OFF_SUP (block 302). The vector of upper threshold values ​​includes a value for each of the combinations. The upper threshold values ​​OFF_SUP thus represent an additional security allowing ensure that the limits of the organs are not exceeded. The upper threshold values ​​OFF_SUP are here strictly greater than zero, they are for example determined empirically during test sessions with the vehicle 10 equipped with the computer 90.

[0081] The result of this comparison is here a vector of booleans (here twenty booleans for the twenty combinations) referenced B_SUP in [Fig.2]. Each boolean is thus associated bijectively with one of the combinations, its value is one when, for said combination, the value of the upper difference DIF_SUP is greater than or equal to the upper threshold value and, conversely, its value is zero when, for said combination, the value of the upper difference DIF_SUP is strictly less than the upper threshold value.

[0082] As regards the lower limit, the computer 90 calculates the difference between the selected current rotation speed V_COU and the selected lower anticipated limit L_ANT_INF (block 303). This difference is calculated in a vector manner. The result of this difference, called the lower difference and referenced DIF_INF in [Fig.2], is therefore a vector, here of twenty values ​​for the twenty combinations, each value being associated bijectively with one of the combinations and being defined as the difference between the value of the selected current rotation speed V_COU and the value of the selected lower anticipated limit L_ANT_INF which are associated with said combination.

[0083] The computer 90 then compares the lower difference DIF_INF to a vector of lower threshold values ​​OFF_INF (block 304). The vector of lower threshold values ​​includes a value for each of the combinations. The lower threshold values ​​OFF_INF thus represent an additional safety feature to ensure that the lower limit of the thermal engine is not exceeded. The lower threshold values ​​OFF_INF are here strictly greater than zero; they are, for example, determined empirically during test sessions with the vehicle 10 equipped with the computer 90.

[0084] The result of this comparison is here a vector of booleans (here twenty booleans for the twenty combinations) referenced B_INF in [Fig.2]. Each boolean is thus associated with one of the combinations, its value is one when, for said combination, the value of the lower difference DIF_INF is greater than or equal to the lower threshold value and, conversely, its value is zero when, for said combination, the value of the lower difference DIF_INF is strictly less than the lower threshold value.

[0085] The method finally comprises a seventh step of validating or not the combinations on the basis of the comparisons made in the sixth step.

[0086] Here, the calculator 90 performs a logical operation of the “and” type (“and” in English) between the Boolean vectors B_SUP, B_INF resulting from the sixth step (block 400). The computer 90 thus constructs a validation vector, referenced V in [Fig.2]. The validation vector V here comprises twenty Booleans for the twenty combinations. Each Boolean of the validation vector V is associated bijectively with one of the combinations and is equal to one when the two Booleans (one for each validation vector B_SUP, B_INF) resulting from the sixth step and associated with said combination are both equal to one. Each Boolean of the validation vector V is equal to zero in the other cases, that is to say when at least one of the Booleans resulting from the sixth step and associated with said combination is equal to zero.

[0087] This validation vector V thus indicates the valid combinations, that is to say those for which the Boolean is equal to one. These valid combinations therefore respect the limits defined for the organs. In contrast, it also indicates the invalid combinations, that is to say those for which the Boolean is equal to zero and which therefore do not respect the limits defined for the organs.

[0088] This validation vector V therefore allows the computer 90 responsible for controlling the powertrain to decide which combinations it can authorize and which combinations it can reject.

[0089] This method allows in particular the computer 90 to determine whether the combination of transmission ratios which is currently used to drive the wheels 31, 32 of the vehicle 10 must be authorized or rejected. In this case, the computer 90 analyzes in particular the boolean of the validation vector V associated with the current combination when the method is implemented (in particular the seventh step). If this boolean is zero, this indicates to the computer 90 to change the combination.

[0090] Thus, a global method for selecting a combination is provided. This global method firstly comprises the method according to the invention applied at least to the current combination. This global method then comprises a step of changing the combination (therefore changing gears) if the current combination is not validated. This global method can also be applied to all the combinations considered (or some of them). When the current combination is not validated, the new combination can be selected from those that have been validated.

[0091] The present invention is in no way limited to the embodiments described and shown, but those skilled in the art will be able to provide any variant in accordance with the invention.

[0092] For example, in terms of traction devices, the powertrain may comprise only the two electric machines (and not the heat engine). The method then concerns only the determination and comparison with upper limits. The powertrain may also comprise only the front electric machine and the heat engine. In this case, the powertrain includes only the front gearbox and front output shaft (not the rear gearbox and output shaft).

[0093] The upper threshold values ​​and the lower threshold values ​​may be equal to zero. The Boolean vectors may then be determined directly from a comparison between the selected anticipated limits and the selected current rotational speed.

[0094] The anticipated limits may not be implemented. This amounts to considering that the reductions and the increase are equal to zero, which is also the case when the derivatives are zero. The upper anticipated limits are then equal to the upper limits and the lower anticipated limit is then equal to the lower limit.

[0095] In the third step, it is possible to acquire only the instantaneous rotation speed of one of the members. According to this variant, it is possible to acquire the instantaneous rotation speed of any of the members. A single current rotation speed is then calculated, in the fourth step, on the basis of the instantaneous rotation speed of this single member. This single current rotation speed is then automatically selected as the current rotation speed selected in the sixth step.

[0096] The method may not be implemented for all combinations in parallel but for only one or some of the predefined combinations, in particular only for the current combination. If it is implemented for only one combination, the variables which are vectors in the example of [Fig.2] may then comprise a single value relating only to this combination.

[0097] As described above, the ratios can be defined not in relation to the number of revolutions of the output shafts but in relation to the number of revolutions of the wheels connected to these output shafts. In this case, the upper rotation limits nevertheless remain "relative" to the output shafts driven by the components since there is a fixed coefficient between the number of revolutions of the wheels and the number of revolutions of the output shafts, (the number of revolutions of the wheels depending linearly on the number of revolutions of the output shafts). Of course, to implement the method, the ratios of all the components (the heat engine and two electrical machines) are defined in the same way, that is to say either directly in relation to the output shafts, or in relation to the wheels.

[0098] The number of discrete ratios of the organs may vary from the examples given previously, as may the number of combinations which may be greater or less than twenty.

[0099] The control of the powertrain can be carried out not by the computer but by a dedicated electronic unit.

[0100] The instantaneous rotational speed variation can be determined on the basis of different sensors of the vehicle. The speed variation can for example be determined on the basis of the states of the accelerator or brake pedals which make it possible to anticipate variations in the speed of the vehicle. The speed variation can also be determined on the basis of measurements of the longitudinal speed of the vehicle.

Claims

Claims

1. Validation method, applied to a powertrain (20) of an electric or hybrid motor vehicle (10) comprising at least two traction members (41, 42, 43) and at least one gearbox (51, 52) adapted to ensure several combinations of transmission ratios between the traction members (41, 42, 43) and at least one output shaft (71, 72) of the gearbox (51, 52), of at least one combination of transmission ratios, the method comprising the following steps: - acquisition of a maximum rotation speed (V_MAX_1, V_MAX_2, V_MAX_3) intrinsic to each member (41, 42, 43); - calculation, for each member (41, 42, 43), on the basis of said combination of transmission ratios and the maximum rotation speed (V_MAX_1, V_MAX_2, V_MAX_3) intrinsic to said member (41, 42, 43), of an upper rotation limit (L_SUP_1, L_SUP_2, L_SUP_3) relating to an output shaft (71, 72) driven by said member (41, 42, 43);- acquisition of an instantaneous rotation speed (V_INS_1, V_INS_2, V_INS_3) of a first of the members (41, 42, 43); - calculation, on the basis of said combination of transmission ratios and the instantaneous rotation speed (V_INS_1, V_INS_2, V_INS_3), of a current rotation speed (V_COU_1, V_COU_2, V_COU_3) relating to the output shaft (71, 72) driven by said first member (41, 42, 43); - validation or not of the combination of transmission ratios on the basis of a comparison between one of said upper rotation limits (L_SUP_1, L_SUP_2, L_SUP_3) and said current rotation speed (V_COU_1, V_COU_2, V_COU_3).;

2. The method of claim 1, wherein said one of said upper rotation limits (L_SUP_1, L_SUP_2, L_SUP_3) used for comparison is the lowest upper rotation limit (L_SUP_1, L_SUP_2, L_SUP_3) among the upper rotation limits (L_SUP_1, L_SUP_2, L_SUP_3) of the at least two members (41, 42, 43).

3. Method according to claim 1 or 2, in which it is provided: - the acquisition of the instantaneous rotation speed (V_INS_1, V_INS_2, V_INS_3) of each member (41, 42, 43); - calculating a current rotation speed (V_COU_1, V_C0U_2, V_C0U_3) for each member (41, 42, 43); and wherein the current rotation speed (V_COU_1, V_C0U_2, V_C0U_3) used for the comparison is the highest current rotation speed (V_COU_1, V_C0U_2, V_C0U_3) among the current rotation speeds (V_COU_1, V_C0U_2, V_C0U_3) of the at least two members (41, 42, 43).

4. Method according to one of claims 1 to 3, wherein the calculation of the upper rotation limit (L_SUP_1, L_SUP_2, L_SUP_3) is based on a ratio (R_l, R_2, R_3), which depends on said combination of transmission ratios, between: - the rotation of said member (41, 42, 43); and - the rotation of the output shaft (71, 72) driven by said member (41, 42, 43) or the rotation of the wheels (31, 32) driven by said member (41, 42, 43).

5. Method according to one of claims 1 to 4, in which the calculation of the current rotation speed (V_COU_1, V_C0U_2, V_C0U_3) is based on a ratio, which depends on said combination of transmission ratios, between: - the rotation of said first member (41, 42, 43); and - the rotation of the output shaft (71, 72) driven by said first member (41, 42, 43) or the rotation of the wheels (31, 32) driven by said member (41, 42, 43).

6. Method according to one of claims 1 to 5, in which it is provided to calculate, for each member (41, 42, 43), an anticipated limit (L_ANT_SUP_1, L_ANT_SUP_2, L_ANT_SUP_3), relating to the output shaft (71, 72) driven by said member (41, 42, 43), which is lower than the upper rotation limit (L_SUP_1, L_SUP_2, L_SUP_3), and in which the comparison is carried out between one of said anticipated rotation limits (L_ANT_SUP_1, L_ANT_SUP_2, L_ANT_SUP_3) and said current rotation speed (V_COU_1, V_C0U_2, V_C0U_3).

7. Method according to claim 6, in which it is provided, for each member (41, 42, 43), to calculate the anticipated rotation limit (L_ANT_SUP_1, L_ANT_SUP_2, L_ANT_SUP_3) on the basis of a temporal variation (D_l, D_2, D_3) of the instantaneous rotation speed (L_ANT_SUP_1, L_ANT_SUP_2, L_ANT_SUP_3) of said member (41, 42, 43).

8. Method according to one of claims 1 to 7, in which it is provided to acquire a minimum rotation speed (V_MIN_1) intrinsic to at least one of the members (41, 42, 43) and to calculate, for said member (41, 42, 43), a lower rotation limit (L_INF_1) relative to the output shaft (71, 72) driven by said member (41, 42, 43), and in which the validation or not of the combination of transmission ratios is also based on a comparison between said lower rotation limit (L_INF_1) and said current rotation speed (V_COU_1).

9. Method according to one of claims 1 to 8, in which said combination of transmission ratios validated or not is the combination which is currently used to drive the wheels (31, 32) of the vehicle (10).

10. Method according to one of claims 1 to 9, in which it is provided: - for each member (41, 42, 43), to calculate an upper rotation limit (L_SUP_1, L_SUP_2, L_SUP_3) for each combination of transmission ratios; - to calculate a current rotation speed (V_COU_1, V_COU_2, V_COU_3) for each combination of transmission ratios; - to validate or not each combination of transmission ratios, each validation or not of a combination of transmission ratios being based on a comparison between one of said upper rotation limits (L_SUP_1, L_SUP_2, L_SUP_3) and said current rotation speed (V_COU_1, V_COU_2, V_COU_3) which are associated with said combination of transmission ratios.

11. Electric or hybrid motor vehicle (10) comprising: - a powertrain (20) which comprises at least two traction members (41, 42, 43) and a gearbox (51, 52) adapted to provide several combinations of transmission ratios between the traction members (41, 42, 43) and at least one output shaft (71, 72); - a computer (90) programmed to implement a method for validating a combination of transmission ratios for controlling the powertrain (20) according to one of claims 1 to 10.

Images