FR3145732A1 - METHOD FOR DETERMINING AN ENGINE TORQUE SETPOINT DURING ACTUATION TRANSIENTS IN THE NEUTRAL OR PARKING POSITION OF THE CONTROL LEVER OF A VEHICLE HYBRID TRANSMISSION - Google Patents

Abstract

The method is implemented in a vehicle having a powertrain (eGMP) comprising a heat engine (MT) and a hybrid transmission system (eTR), the group having phases of electrical generation by driving by the engine of an electric machine coupled via a clutch (K0), these phases occurring when a control lever (LC) of the transmission system is placed in a neutral position (N) or a parking position (P). According to the invention, the method comprises the steps of A) detecting a transition of the lever to the N or P position, occurring jointly with a control under load of the engine/clutch/electric machine assembly, and B), when a transition is detected in step A) with a control under load, determining a heat engine torque setpoint as a function of torque information transmitted by the clutch which is established from at least one observed variable of the engine. Figure 1

Description

METHOD FOR DETERMINING AN ENGINE TORQUE SETPOINT DURING ACTUATION TRANSIENTS IN THE NEUTRAL OR PARKING POSITION OF THE CONTROL LEVER OF A VEHICLE HYBRID TRANSMISSION

The present invention relates generally to the field of hybrid thermal-electric powertrains for motor vehicles. More particularly, the invention relates to a method for determining the engine torque during transients of actuation in the neutral or parking position of the control lever of a vehicle hybrid transmission system.

In hybrid vehicles, dual-clutch hybrid transmission systems, known as “eDCT” for “electric Dual Clutch Transmission” in English, contribute to the optimization of energy efficiency, for a reduction in consumption and pollutant emissions. “eDCT” transmission systems provide many advantages, particularly in terms of weight, compactness, flexibility of energy management and others. They are applicable in different known powertrain architectures, such as the mild hybrid architecture, known as “mild-hybrid” or “MHEV” for “Mild Hybrid Electric Vehicle” in English, the complete hybrid architecture, known as “full-hybrid” or “(F)HEV” for “(Full) Hybrid Electric Vehicle” in English, and the rechargeable hybrid architecture known as “plug-in hybrid” or “PHEV” for “Plug-in Hybrid Electric Vehicle” in English.

There schematically illustrates an eGMP hybrid powertrain of a hybrid electric vehicle. The vehicle considered here is of the PHEV type, for example, and integrates three traction modes, namely, a thermal traction mode, an electric traction mode and a hybrid traction mode.

The eGMP group includes an MT thermal engine and an “eDCT” type transmission system identified as eTR. The eTR transmission system is equipped with a DCT dual-clutch robotized gearbox, an ME rotating electric machine and a K0 clutch device.

The DCT gearbox typically comprises a K12 dual clutch device and GR gear trains, as well as actuators and synchronizers (not shown) for the robotized shifting of transmission ratios. The DCT gearbox receives a mechanical traction torque via its input shaft AE for the rotational drive of the WH wheels of the vehicle coupled to its output shaft AS.

The rotating electrical machine ME is mechanically coupled by gears to the input shaft AE of the DCT gearbox according to a so-called “P2” architecture. The ME machine is connected to an electric traction storage device (not shown) of the vehicle via a reversible electric power converter (not shown). The ME machine operates in electric motor mode for the electric traction of the vehicle and the starting of the thermal engine MT and in electric generator mode for the generation of electrical energy via a drive by the thermal engine MT and for regenerative braking.

The K0 clutch device fulfils a coupling/decoupling function in the transmission of mechanical torque between the MT combustion engine and the eTR transmission system. Thus, with the K0 clutch device open, the MT combustion engine is disconnected from the drive train, which allows in the electric traction mode by the ME machine, as well as in the regenerative braking mode, to avoid friction losses due to the MT combustion engine, for better energy efficiency. With the K12 double clutch device open and the K0 clutch device closed, the ME machine is disconnected from the transmission to the WH wheels and is only engaged with the MT combustion engine, which allows the MT combustion engine to be started with the ME machine in motor mode and the generation of electrical energy by driving the MT combustion engine of the ME machine in generator mode.

The different operating modes and life phases of the eGMP hybrid powertrain are managed by a supervisor ECU_S, an engine control ECU_E and a transmission control ECU_T which are connected to a BCD data communication bus, typically of the “CAN” type. The supervisor ECU_S is responsible for the overall management of the eGMP group, the ECU_E and ECU_T being responsible for the close management of the ME thermal engine and the eTR transmission system, respectively. The ECU_S, ECU_E and ECU_T computers collaborate with each other to implement different control strategies depending on the actions of the vehicle driver and life situations.

Through the BCD data communication bus, the supervisor computer ECU_S receives in particular commands from the driver, information from the vehicle computers and/or information from various sensors, and transmits information and commands to the computers ECU_E and ECU_T for controlling the eGMP powertrain. Thus, the supervisor computer ECU_S receives in particular information on the position PP of a control lever LC manipulated by the driver to control the movement of the vehicle. Typically, the positions of the control lever LC comprise at least two driving positions, namely, the forward gear D and the reverse gear R, a neutral position N and a parking position P, as well as a position (not shown) for manually changing transmission gears.

The inventive entity noted a difficulty in controlling the assembly formed by the thermal engine MT, the clutch device K0 and the electric machine ME, hereinafter referred to as MT/K0/ME, in situations of electrical generation for recharging the electric storage device occurring when the lever LC is placed in the neutral position N or in the parking position P and the electric machine ME is driven by the thermal engine MT. During the transition phase of the lever LC from the neutral position N to the parking position P, or vice versa, the estimation of the torque transmitted by the clutch device K0 lacks precision and this results in difficulty in controlling the control of the assembly MT/K0/ME. Thus, deficient control when opening the clutch device K0 can lead to the occurrence of shock phenomena, soaring of the thermal engine MT speed and under-speed of the electric machine ME which propagate into the passenger compartment of the vehicle and impair passenger comfort. Shock phenomena can also occur when closing the K0 clutch device, due to an incorrectly adjusted speed command supplied to the MT thermal engine and resulting from the lack of precision in the estimation of the torque transmitted by the K0 clutch device.

This lack of precision in the estimation of the torque transmitted by the K0 clutch device during transitions to the neutral position N or the parking position P results from the hydraulic control architecture of the eTR transmission system. Indeed, during these transient phases, the hydraulic pressure in the K0 clutch device must be reduced, which consequently generates a drop in the transmitted torque during which the estimation of the latter is imprecise. Once the position of the LC lever has stabilized, at the neutral position N or the parking position P, the hydraulic pressure in the K0 clutch device increases. The transmitted torque can then be estimated with the required precision for satisfactory control of the MT/K0/ME assembly.

Document FR3068666A1 describes the triggering of a recharge of an electric traction storage device in a hybrid vehicle when the gearbox control lever is placed in the neutral position or the parking position. The rotating electric machine of the vehicle is then driven by the thermal engine and recharges the electric storage device.

The present invention aims to provide a solution to the drawback set out above of the state of the art.

According to a first aspect, the invention relates to a method for determining a thermal engine torque setpoint implemented in a hybrid electric vehicle having a powertrain comprising a thermal engine and a hybrid transmission system, the hybrid transmission system having a rotating electric machine coupled to the thermal engine via a clutch device, the powertrain having phases of electrical generation by driving the rotating electric machine by the thermal engine occurring when a control lever of the hybrid transmission system is placed in a neutral position or a parking position. According to the invention, the method comprises the steps of A) detecting a transition of actuation of the control lever towards the neutral position, or the parking position, occurring jointly with a command for driving under load of the assembly formed by the heat engine, the clutch device and the rotating electrical machine, and B), when said transition is detected in step A) jointly with said command for driving under load, determining the heat engine torque setpoint as a function of information representative of a torque transmitted by the clutch device which is established from at least one observed variable of the heat engine.

Thus, when a transition of actuation of the control lever towards the neutral position, or the parking position, is detected jointly with a loaded steering command, the invention makes it possible not to use an estimated variable transmitted by a transmission computer, thus compensating for the lack of precision observed in the prior art.

According to a particular characteristic, the torque information transmitted by the clutch device is established from an engine speed, an engine torque and an engine inertia.

The invention also relates to a calculator comprising a memory storing program instructions for implementing the method briefly described above. Preferably, the calculator is an engine control calculator of the vehicle.

The invention also relates to a hybrid electric vehicle having a powertrain comprising a heat engine and a hybrid transmission system, the hybrid transmission system having a rotating electric machine coupled to the heat engine via a clutch device, the powertrain having phases of electrical generation by driving the rotating electric machine by the heat engine occurring when a control lever of the hybrid transmission system is placed in a neutral position or a parking position, and comprising a computer as indicated above. Preferably, the hybrid transmission system comprises a dual-clutch gearbox.

Other advantages and characteristics of the present invention will appear more clearly on reading the detailed description below of several particular embodiments of the invention, with reference to the appended drawings, in which:

There is a block diagram schematically showing an architecture of a hybrid electric vehicle powertrain equipped with a dual-clutch hybrid transmission system.

There is a functional block diagram showing an implementation of the method of the invention in the powertrain of the .

In reference to the and the , a particular embodiment of the method according to the invention is now described. The method is here implemented in a hybrid powertrain, such as the eGMP group of the , comprising a thermal engine and a dual-clutch hybrid transmission system of the “eDCT” type, designated respectively by their MT and eTR references.

In general, the method according to the invention determines an engine torque setpoint for regulating the speed of the heat engine which, compared to that used in the prior art, is modified when a transition of the lever of the transmission system to the neutral position N or parking position P is detected jointly with the detection of a control command under load of the assembly formed by the heat engine, the clutch device and the electric machine.

With particular reference to the , an embedded engine speed control software system SRE is typically hosted in the engine control computer ECU_E dedicated to the management of the MT thermal engine. Generally, the engine control computer ECU_E hosts several strategies for controlling and regulating the speed of the MT thermal engine which are activated according to the different life situations of the vehicle. An engine torque setpoint CCM is determined by the engine speed control system SRE and is used for controlling the MT thermal engine.

The engine speed control software system SRE is located in a memory MEM of the ECU_E computer and includes in particular a software module M_CM whose function is to determine the engine torque setpoint CCM and a software module M_CT whose function is to establish ICT information representative of the torque transmitted by the clutch device K0.

The M_CM software module implements an algorithm which determines the CCM engine torque setpoint based in particular on the transmitted torque information ICT which is provided to it as input by the M_CT software module.

The software module M_CT authorizes the implementation of the method according to the invention by the execution of program code instructions by a processor (not shown) of the calculator ECU_E. The calculator ECU_E, under the supervision of the software module M_CT, cooperates in particular with the supervisor calculator ECU_S and the transmission control calculator ECU_T for the implementation of the method according to the invention.

As visible in the , the M_CT software module essentially includes three functional blocks CD, SL, and M_CTo.

The functional block CD is responsible for detecting, from the lever position information PP and a load piloting control information PC, the joint satisfaction of a condition C1 of transition of the control lever LC to the neutral position N, or the parking position P, and of a condition C2 of a load piloting of the assembly (MT/K0/ME) formed of the thermal engine MT, the clutch device K0 and the electric machine ME. When the aforementioned conditions C1 and C2 are satisfied, the functional block CD outputs a switching command CS, in an active state CS= “1”, which is supplied to the functional block SL.

The SL functional block provides a selection function between first and second values CTe and CTo attributable to the transmitted torque information ICT used to determine the CCM engine torque setpoint.

Thus, when the conditions C1 and C2 are not satisfied, the switching command CS is in an inactive state CS= “0” and the value CTe is assigned to the transmitted torque information ICT, ICT = CTe. The value CTe is the estimation of the torque transmitted by the clutch device K0, which is provided by a transmitted torque estimation function M_CTe hosted in the transmission control computer ECU_T. In this life situation, the system operates in a conventional manner by taking into account the transmitted torque estimation CTe to determine the engine torque setpoint CCM.

When conditions C1 and C2 are satisfied, the switching command CS is in the active state CS = “1” and the value CTo is assigned to the transmitted torque information ICT, ICT = CTo. The value CTo is provided by the functional block M_CTo. The function of the functional block M_CTo is to provide a transmitted torque value, namely CTo, based on observed values of one or more variables or characteristics of the thermal engine MT. Typically, the functional block M_CTo is a previously established mapping which gives the appropriate CTo value to be provided to the algorithm M_CM, a value which is determined here as a function of the engine speed RM, the engine torque CM and the engine inertia IM.

Alternatively, instead of a mapping, the M_CTo functional block could be implemented in the form of a mathematical model calculating the CTo value based on the aforementioned variables and characteristics of the heat engine.

The present invention provides a low-cost, software-based solution for improving the comfort of vehicle users in the particular life situations described above. The proposed solution is suitable for meeting the architectural needs and constraints of different types of hybrid electric vehicles.

The invention is not limited to the particular embodiments which have been described here by way of example. Those skilled in the art, depending on the applications of the invention, will be able to make various modifications and variations falling within the scope of protection of the invention.

Claims (6)

Method for determining a thermal engine torque setpoint (CCM) implemented in a hybrid electric vehicle having a powertrain (eGMP) comprising a thermal engine (MT) and a hybrid transmission system (eTR), said hybrid transmission system (eTR) having a rotating electric machine (ME) coupled to said thermal engine (MT) via a clutch device (K0), said powertrain (eGMP) having electrical generation phases by driving said rotating electric machine (ME) by said thermal engine (MT) occurring when a control lever (LC) of said hybrid transmission system (eTR) is placed in a neutral position (N) or a parking position (P), characterized in that it comprises the steps of A) detecting (CD) an actuation transition (PP, C1) of said control lever (LC) to said neutral position (N), or said parking position (P), occurring jointly with a load control command (PC, C2) of the assembly formed by said thermal engine (MT), said device clutch device (K0) and said rotating electrical machine (ME), and B) when said actuation transition (PP, C1) is detected in step A) together with said on-load control command (PC, C2), determining said thermal engine torque setpoint (CCM) as a function of information (ICT) representative of a torque transmitted by said clutch device (K0) which is established from at least one observed variable (RM, CM, IM) of said thermal engine (MT). Method according to claim 1, characterized in that said information (ICT) is established from an engine speed (RM), an engine torque (CM) and an engine inertia (IM). Calculator comprising a memory (MEM) storing program instructions (M_CT, M_CM) for implementing the method according to claim 1 or 2. Calculator according to claim 3, characterized in that said calculator is an engine control calculator (ECU_M). Hybrid electric vehicle having a powertrain (eGMP) comprising a heat engine (MT) and a hybrid transmission system (eTR), said hybrid transmission system (eTR) having a rotating electric machine (ME) coupled to said heat engine (MT) via a clutch device (K0), said powertrain (eGMP) having phases of electrical generation by driving said rotating electric machine (ME) by said heat engine (MT) occurring when a control lever (LC) of said hybrid transmission system (eTR) is placed in a neutral position (N) or a parking position (P), characterized in that it comprises a computer (ECU_M) according to claim 3 or 4 for controlling said heat engine (MT). Electric hybrid vehicle according to claim 5, characterized in that said hybrid transmission system (eTR) comprises a dual clutch gearbox (DCT).