Method for selecting a target state of a vehicle driveline

Abstract

A method for selecting a target state of a vehicle driveline from a set of states present in a transmission, the vehicle driveline connecting several drive members including an internal combustion engine and at least one electric machine to wheels of the vehicle through the transmission, the set of states being defined by different combinations of couplings and their reduction gears so as to transmit torque from the internal combustion engine and / or from the electric machine to the wheels with one or more gear reduction ratios, characterized in that the selection of the target state comprises a step of determining a minimum (DLS_MIN_RELIA_VH_SPD) and a maximum (DLS_MAX_RELIA_VH_SPD) travel speed of the vehicle, so as to ensure the mechanical reliability of the drive members in each available state of the driveline.

Description

[0001] The present invention relates to hybrid powertrain control.

[0002] More particularly, the present invention relates to a method for selecting a target state of a vehicle powertrain from a set of states existing in a transmission, the vehicle powertrain connecting several drive members, including an internal combustion engine and at least one electric machine, to the wheels of the vehicle through a transmission, the set of states being defined by different combinations of couplings and their reduction gears, in order to transmit the torque from the internal combustion engine and / or from the electric machine to the wheels with one or more gear reduction ratios.

[0003] The mechanical limits of a powertrain are linked to the gear reduction ratios of its transmission, to the speed limits of the drive members and to its specific operating characteristics. These limits must always be determined in order to provide the information required for the state selection strategy in time.

[0004] A hybrid vehicle generally comprises a set of drive members forming its powertrain, including at least one internal combustion engine and one electric machine. The powertrain of a hybrid vehicle has several operating limits imposed by the minimum / maximum rotational speeds of the rotating parts, in particular of its drive members; beyond these speeds, the drive members are in an under-speed or over-speed state, with a high risk of mechanical failure.

[0005] In order to eliminate this risk on an internal combustion engine vehicle, it is sufficient to add the minimum and maximum speed values of the internal combustion engine to the gear shift strategy in parallel with the current speed value. Due to the diversity of the drive members and the operating modes of the powertrain, this information becomes insufficient for a hybrid vehicle.

[0006] The states of a hybrid vehicle powertrain can be defined as combinations of couplings and reduction gears, specific to the vehicle architecture and to its powertrain. The state selection strategy must take into account the mechanical limits of all the drive members. These strategies must be able to anticipate changes of state, in particular to avoid under-speed or over-speed due to the dynamics of the vehicle and the reaction time of the powertrain to perform the state change. For the same purpose, these strategies sometimes need to temporarily freeze a specific target state.

[0007] FR 3 023 526 discloses a method for determining the target state of a powertrain by various decisions, which allows to continuously eliminate states that are not suitable for the situation encountered. One of the decisions implemented concerns maintaining the reliability limits in terms of speed of the drive members. However, this document does not specify how to calculate this information.

[0008] FR 3 013 019 discloses another method for avoiding overspeeding of the drive member, by calculating an expected speed, comparing this expected speed with a limit speed ensuring the reliability of the powertrain. However, there is no expression of how this information is calculated.

[0009] The present invention aims at ensuring the mechanical reliability of a powertrain of a hybrid vehicle by taking into account specific features of the constraints imposed by the transmission and the drive members of the powertrain.

[0010] To this end, the selection of the target state comprises a step of determining a minimum travel speed and a maximum travel speed of the vehicle, so as to ensure the mechanical reliability of the drive member in each available state of the powertrain.

[0011] Preferably, the raw travel speed is calculated according to:

[0012] - the maximum travel speed allowed by the electric machine, and

[0013] - the minimum travel speed and the maximum travel speed allowed by the internal combustion engine.

[0014] The present invention will be more clearly understood on reading the following description of non-limiting embodiments thereof, the said description being given with reference to the attached drawings.

[0015] [ Figure 1 ] is the proposed method flow Figure 1 .

[0016] The method can provide a powertrain computer in charge of selecting a target state of a powertrain of a hybrid vehicle with real-time information across functions. The powertrain can be provided with an internal combustion engine and a single drive electric machine, like in the powertrain of (can be referred to) EP 2 694 309, and comprises two concentric main shafts, each having at least one intermediate drive on a secondary shaft connected to the wheels of the vehicle. The architecture described in this publication provides a non-limiting application of the method concerned by the present invention.

[0017] The item of information across functions provided to the computer is the minimum travel speed and the maximum travel speed of the vehicle that can be achieved in each available powertrain state in order to meet the reliability constraints related to the rotational speed of the drive member.

[0018] This information is used to select a target state of a powertrain connecting a plurality of drive members including an internal combustion engine and at least one electric machine to the wheels of a vehicle through a transmission. The selection is made from a set of states existing on the transmission, defined by different combinations of couplings and their reduction gears, in order to transmit the torque from the internal combustion engine and / or from the electric machine to the wheels with one or more gear reduction ratios.

[0019] Figure 1 All the input data items necessary for determining the cross-functional information are shown:

[0020] - MAX EM SPD is the maximum speed that the main drive machine can reach; this data item is updated in real time by the function in charge of actuating the electric machine;

[0021] - ICE TEMP is the water temperature of the internal combustion engine, updated in real time;

[0022] - MAX ICE SPD is the maximum speed that can be reached by the internal combustion engine; if the electric machine is coupled to the internal combustion engine, MAX ICE SPD takes into account its maximum allowed speed; MAX ICE SPD is updated in real time by the function in charge of actuating the internal combustion engine;

[0023] - DLS TGT is the current target state of the driveline;

[0024] - DLS TYP LIST is a vector of state energy types (internal combustion, electric or hybrid); this vector makes it possible to know the state types available in the driveline and their energy definition;

[0025] - DLS TYP LIST is provided by a third-party function, specific to each driveline, and does not change during its operation;

[0026] - PAR LIMIT ENA is an adjustment parameter, taking the value 1 or 0. PAR LIMIT ENA takes the value 1 when the driveline only comprises a single drive electric machine whose maximum speed limit is to be taken into account and when this limit cannot be included in the maximum speed value of the internal combustion engine, MAX ICE SPD, because the electric machine is not directly mechanically linked to the internal combustion engine; this is the case in the architecture described in EP 2 694 309, in which the electric machine can be uncoupled and have different gear reduction ratios on the internal combustion engine and on the electric machine; in other cases, in particular when there is a second electric machine directly coupled to the internal combustion engine, PAR LIMIT ENA takes the value 0.

[0027] The selection of the target state includes the step of determining the minimum and maximum travel speeds of the vehicle, DLS MIN RELIA VH SPD and DLS MAX RELIA VH SPD, so as to be able to ensure the mechanical reliability of the drive members in each available state of the driveline.

[0028] The state types of the vector DLS TYP LIST can be as follows:

[0029] - HEV SER: series hybrid drive;

[0030] - HEV_SER_RVR: motor reverse series hybrid drive;

[0031] - HEV_PAR: parallel hybrid drive;

[0032] - HEV_SER_PAR: series-parallel hybrid drive;

[0033] - TH: internal combustion drive;

[0034] - EV: electric drive;

[0035] - EV_RVR: motor reverse electric drive;

[0036] - NEUTRAL: no drive (no drive member connected to the wheels);

[0037] - ABSENT: powertrain state not defined on the vehicle.

[0038] The output information is sent to the vehicle's computing unit in charge of selecting the powertrain state. This information is preferably in the form of a vector. The vectors DLS_MIN_RELIA_VH_SPD and DLS_MAX_RELIA_VH_SPD represent the minimum and maximum travel speeds of the vehicle, so as to ensure the mechanical reliability of the drive members in each state of the powertrain.

[0039] During implementation of the method, the raw values of the travel speeds DLS_MIN_RELIA_VH_SPD_RAW and DLS_MAX_RELIA_VH_SPD_RAW are determined as a function of:

[0040] - the maximum travel speed allowed by the electric machine DLS_MAX_EM_VH_SPD, and

[0041] - the minimum travel speed DLS_MIN_ICE_VH_SPD and the maximum travel speed DLS_MAX_ICE_VH_SPD allowed by the internal combustion engine.

[0042] The function F1 determines the vector of maximum travel speeds allowed in each state of the powertrain DLS_MAX_EM_VH_SPD as a function of the maximum possible speed of the electric machine MAX_EM_SPD, the wheel radius WHEEL_RAD and the vector of gear reduction ratios between the electric machine and the wheels DLS_EM_RATIO. The parameters WHEEL_RAD and DLS_EM_RATIO are specific to the vehicle. The maximum travel speed allowed by the electric machine is calculated in km / h as follows:

[0043] DLS_MAX_EM_VH_SPD = MAX_EM_SPD * WHEEL_RAD * DLS_EM_RATIO

[0044] (MAX EM SPD) * (DLS EM RATIO) * (WHEEL RAD) * (3.6) * (II / 30).

[0045] The raw value of the minimum travel speed DLS MIN RELIA VH SPD RAW and the raw value of the maximum travel speed DLS MAX RELIA VH SPD RAW of the vehicle are determined at each available state according to the drive energy type DLS TYP LIST (X) of this state.

[0046] The function F2 determines the minimum travel speed vector DLS MIN ICE VH SPD and the maximum travel speed vector DLS MAX ICE VH SPD allowed according to the internal combustion engine at each state according to the minimum speed MIN ICE SPD and the maximum speed MAX ICE SPD possible for the internal combustion engine, the wheel radius WHEEL RAD and the gear reduction ratio DLS ICE RATIO between the internal combustion engine and the wheels.

[0047] The parameter MIN ICE SPD represents the minimum rotational speed allowed for the internal combustion engine. MIN ICE SPD is a function of the internal combustion engine water temperature ICE TEMP. This value can be given by a configurable table with ICE TEMP as input data item. This value can also be directly provided by the function in charge of actuating the internal combustion engine in the powertrain control system. The parameters WHEEL RAD and DLS ICE RATIO are specific to the vehicle. These speeds are calculated in km / h as follows:

[0048] DLS MAX ICE VH SPD = (MAX ICE SPD) * (DLS ICE RATIO) * (WHEEL RAD) * (3.6) * (II / 30), and

[0049] DLS MIN ICE VH SPD = (MIN ICE SPD) * (DLS ICE RATIO) * (WHEEL RAD) * (3.6) * (II / 30).

[0050] DLS MAX ICE VH SPD = (MAX ICE SPD) * (DLS ICE RATIO) * (WHEEL RAD) * (3.6) * (II / 30), and

[0051] DLS MIN ICE VH SPD = (MIN ICE SPD) * (DLS ICE RATIO) * (WHEEL RAD) * (3.6) * (II / 30).

[0052] The function F3 determines, from the energy type of each state, the vector that combines the minimum DLS_MIN_RELIA_VH_SPD_RAW and maximum DLS_MAX_RELIA_VH_SPD_RAW vehicle speed limits that can be achieved in each state of the driveline. The states of the vector DLS_TYP_LIST include at least one neutral state, one electric state and one internal combustion state.

[0053] Depending on the state energy type X of the state in question with the value DLS_TYP_LIST(X), these values are defined in the vector DLS_TYP_LIST:

[0054] - ABSENT state (not defined on the vehicle):

[0055] DLS_MIN_RELIA_VH_SPD_RAW(X) = 0 km / h and

[0056] DLS_MAX_RELIA_VH_SPD_RAW(X) = 0 km / h;

[0057] - NEUTRAL state: DLS_MIN_RELIA_VH_SPD_RAW(X) = 0 km / h, and DLS_MAX_RELIA_VH_SPD_RAW(X) is not actually limited and can take a very high value;

[0058] - TH state: (internal combustion): DLS_MIN_RELIA_VH_SPD_RAW(X) = DLS_MIN_ICE_VH_SPD(X) and DLS_MAX_RELIA_VH_SPD_RAW(X) = DLS_MAX_ICE_VH_SPD(X);

[0059] - EV state (electric) or EV_RVR state (reverse electric): DLS_MIN_RELIA_VH_SPD_RAW(X) = 0 km / h and DLS_MAX_RELIA_VH_SPD_RAW(X) = DLS_MAX_EM_VH_SPD(X);

[0060] - HEV_SER state (series hybrid drive) or HEV_SER_RVR state: (reverse series hybrid drive): DLS_MIN_RELIA_VH_SPD_RAW(X) = 0 km / h, and DLS_MAX_RELIA_VH_SPD_RAW(X) = DLS_MAX_EM_VH_SPD(X);

[0061] - HEV_SER_PAR state (series hybrid): DLS_MIN_RELIA_VH_SPD_RAW(X) = DLS_MIN_ICE_VH_SPD(X) and DLS_MAX_RELIA_VH_SPD_RAW(X) = min(DLS_MAX_ICE_VH_SPD(X), DLS_MAX_EM_VH_SPD(X));

[0062] - HEV_PAR state (parallel hybrid): DLS_MIN_RELIA_VH_SPD_RAW(X) = DLS_MIN_ICE_VH_SPD(X).

[0063] The adjustment parameter PAR_LIMIT_ENA can take the value 1 or 0. It is equal to 1 when the powertrain has only a single electric machine and its maximum speed limit is not included in the value of the maximum speed of the internal combustion engine MAX_ICE_SPD. In this case, DLS_MAX_RELIA_VH_SPD_RAW(X) is equal to the minimum of DLS_MAX_ICE_VH_SPD(X) and DLS_MAX_EM_VH_SPD(X).

[0064] PAR_LIMIT_ENA takes the value 0 in other cases. If PAR_LIMIT_ENA = 0, then DLS_MAX_RELIA_VH_SPD_RAW(X) is equal to DLS_MAX_ICE_VH_SPD(X).

[0065] In other words, when the powertrain has only a single electric machine, the maximum speed limit of this machine MAX_EM_SPD is not included in the value of the maximum speed of the internal combustion engine MAX_ICE_SP, the raw maximum speed of the vehicle DLS_MAX_RELIA_VH_SPD_RAW(X) is the minimum of the maximum speeds allowed by the internal combustion engine and the electric machine, DLS_MAX_ICE_VH_SPD(X) and DLS_MAX_EM_VH_SPD(X).

[0066] In other arrangements of the powertrain, the raw maximum speed of the vehicle DLS_MAX_RELIA_VH_SPD_RAW(X) is equal to the maximum speed allowed by the internal combustion engine DLS_MAX_ICE_VH_SPD(X).

[0067] Finally, the function F4 merges the vectors DLS_MIN_RELIA_VH_SPD_RAW and DLS_MAX_RELIA_VH_SPD_RAW related to the limited travel speed of the vehicle in each state of the powertrain.

[0068] The first merging consists in subtracting or adding the vehicle speed offset SPD OFS in the set of reliability limits calculated for each different state of the current target DLS TGT. The original minimum travel speed DLS MIN RELIA VH SPD RAW and the original maximum travel speed DLS MAX RELIA VH SPD RAW of the vehicle, in all the different available states of the current target DLS TGT, are respectively merged by adding or subtracting the speed offset SPD OFS.

[0069] This offset reduces the available speed range, as a margin between the achievable actual value and the calculated limit speed specified in the upstream function used to select the target state using this information is deducted from the available speed range. These merged limit travel speed values are respectively called DLS MIN RELIA VH SPD CS and DLS MIN RELIA VH SPD CS, where:

[0070] DLS MIN RELIA VH SPD CS = DLS MIN RELIA VH SPD RAW + SPD OFS except for the coordinates of the current target DLS TGT, with DLS MIN RELIA VH SPD CS = DLS MIN RELIA VH SPD RAW, and

[0071] DLS MAX RELIA VH SPD CS = DLS MAX RELIA VH SPD RAW - SPD OFS except for the coordinates of the current target DLS TGT, with DLS MAX RELIA VH SPD CS = DLS MAX RELIA VH SPD RAW.

[0072] The second merging aims to impose a specific minimum value on the state of the driveline if the state of the driveline can be achieved through slippage of the coupling located between the machine or internal combustion engine used and the wheels; this specific value makes it possible to achieve a state of the driveline at a lower vehicle travel speed than the calculated nominal value. It is also possible to impose a minimum speed on the state of the driveline, thus allowing the vehicle to move off from zero speed and drive the vehicle using only the electric machine. Thus, in the state of the driveline that can be achieved due to slippage of the coupling at a lower travel speed than the calculated nominal travel speed, or in the state of the driveline that allows the vehicle to move off from zero speed and drive the vehicle using only the electric machine, these original minimum speeds DLS MIN RELIA VH SPD CS are merged by imposing a specific minimum value on the original minimum speed DLS MIN RELIA VH SPD CS.

[0073] To this end, the adjustment parameter DLS_VS_MIN_ENA is applied; this parameter is a vector that specifies a replacement value DLS_VS_MIN_VALUE for each state and makes it possible to determine whether the calculated minimum speed value DLS_MIN_RELIA_VH_SPD_CS must be used or replaced with the specified replacement value.

[0074] If the X coordinate of the vector DLS_VS_MIN_ENA is equal to 1, the X coordinate value of DLS_MIN_RELIA_VH_SPD is equal to the X coordinate value of DLS_VS_MIN_VALUE. Otherwise (DLS_VS_MIN_ENA = 0), the X coordinate value of DLS_MIN_RELIA_VH_SPD is equal to the merged value of the X coordinate of DLS_MAX_RELIA_VH_SPD_CS.

[0075] Through all these functions, the minimum travel speed and the maximum travel speed of the vehicle can ensure that the mechanical reliability in terms of rotational speed of the drive members in each state of the powertrain is calculated in real time and automatically. These values allow any strategy using this information, in particular the calculation unit performing the selection of the target state of the powertrain, to be aware of these limits of their own operation.

[0076] This method has many advantages. The implemented strategy is fully cross-functional. The strategy can be applied to any vehicle with a hybrid / electric / conventional powertrain, with an automatic transmission with discrete gear ratios, at least one electric state, one internal combustion state and / or one hybrid state.

Claims

1. A method for selecting a target state of a vehicle driveline from a set of states present in a transmission, the vehicle driveline connecting several drive members including an internal combustion engine and at least one electric machine to wheels of the vehicle through the transmission, the set of states being defined by different combinations of couplings and their gear reduction ratios so as to transmit torque from the internal combustion engine and / or from the electric machine to the wheels with one or more gear reduction ratios, the selection of the target state including a step of determining a minimum (DLS_MIN_RELIA_VH_SPD) and a maximum (DLS_MAX_RELIA_VH_SPD) travel speed of the vehicle so as to ensure mechanical reliability of the drive members in each available state of the driveline, characterized in that: - the maximum travel speed allowed by the electric machine (DLS_MAX_EM_VH_SPD) is a function of the maximum speed possible of the electric machine (MAX_EM_SPD), of the wheel radius (WHEEL_RAD) and of the gear reduction ratio between the electric machine and the wheels (DLS_EM_RATIO), and - the minimum (DLS_MIN_ICE_VH_SPD) and the maximum (DLS_MAX_ICE_VH_SPD) travel speed allowed according to the internal combustion engine are a function of the minimum and maximum speeds possible of the internal combustion engine (MIN_ICE_SPD, MAX_ICE_SPD), of the wheel radius (WHEEL_RAD) and of the gear reduction ratio between the internal combustion engine and the wheels (DLS_ICE_RATIO), wherein the raw minimum (DLS_MIN_RELIA_VH_SPD_RAW) and the raw maximum (DLS_MAX_RELIA_VH_SPD_RAW) travel speed of the vehicle are determined from: - the maximum travel speed allowed by the electric machine (DLS_MAX_EM_VH_SPD), and - the minimum (DLS_MIN_ICE_VH_SPD) and the maximum (DLS_MAX_ICE_VH_SPD) travel speed allowed according to the internal combustion engine.

2. The method of claim 1, wherein, The raw minimum (DLS_MIN_RELIA_VH_SPD_RAW) and the raw maximum (DLS_MAX_RELIA_VH_SPD_RAW) travel speed of the vehicle are determined in each available state from the drive energy type of the state (DLS_TYP_LIST(X)).

3. The method of claim 1 or 2, wherein, When the vehicle driveline has only a single electric machine, the maximum speed limit of the electric machine (MAX_EM_SPD) is not included in the value of the internal combustion engine maximum speed (MAX_ICE_SPD), the raw maximum speed of the vehicle (DLS_MAX_RELIA_VH_SPD_RAW(X)) is the minimum of the maximum speeds allowed by the internal combustion engine and the electric machine (DLS_MAX_ICE_VH_SPD(X)) and (DLS_MAX_EM_VH_SPD(X)).

4. The method of claim 3, wherein, In other arrangements of the vehicle driveline, the raw maximum speed of the vehicle (DLS_MAX_RELIA_VH_SPD_RAW(X)) is equal to the maximum speed allowed by the internal combustion engine (DLS_MAX_ICE_VH_SPD(X)).

5. The method of claim 1 or 2, wherein, In all available states different from the current target (DLS_TGT), the raw minimum travel speed (DLS_MIN_RELIA_VH_SPD_RAW) and the raw maximum travel speed (DLS_MAX_RELIA_VH_SPD_RAW) of the vehicle are merged by adding or subtracting a speed offset (SPD_OFS), respectively.

6. The method of claim 1 or 2, wherein, In the driveline states that can be achieved at travel speeds lower than the nominal calculated travel speed due to slippage of the coupling, or in the driveline states that allow the vehicle to depart from zero speed and drive the vehicle using only the electric machine, these speeds are merged by imposing specific minimum values on the minimum speed (DLS_MIN_RELIA_VH_SPD_CS) and on the maximum speed (DLS_MAX_RELIA_VH_SPD_CS).

7. The method of claim 1 or 2, wherein, The vector of state energy types (DLS_TYP_LIST) comprises at least one neutral state, one electric state and one internal combustion state.

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