HYBRID MOTOR VEHICLE COMPRISING AN OPERATING TORQUE LIMITING MEANS, METHOD AND PROGRAM BASED ON SUCH A VEHICLE

Abstract

The invention relates to a motor vehicle comprising:- a heat engine (MT);- a coupling means (K0);- an electric machine (ME);- a gearbox (BV) and a clutch system (K1, K2);- at least one axle (R);- a calculation means for calculating a maximum transmissible torque corresponding to the torque supplied by the heat engine (MT) coupled to the electric machine (ME) at the current gear;- a calculation means for calculating a maximum operating torque from the maximum transmissible torque and a transfer function minimizing the maximum transmissible torque;- a torque control means limiting the torque applied to the axle (R) to the maximum operating torque. The invention also relates to a method and a program based on such a vehicle. Figure 1

Description

Title of the invention: HYBRID MOTOR VEHICLE INCLUDING AN OPERATING TORQUE LIMITING MEANS, METHOD AND PROGRAM BASED ON SUCH A VEHICLE

[0001] The invention relates to the field of engine control systems, in particular torque control systems applied in hybrid vehicles where the thermal engine and the electric motor are coupled together.

[0002] The architecture suitable for the invention is illustrated in [Fig.l]. It is composed of a thermal engine MT, a clutch KO (separation clutch allowing electric driving without the losses of the thermal engine), an electric machine ME in position called P2, namely between the gearbox BV and the thermal engine MT.

[0003] On this type of powertrain, the torque requested by the driver is achieved by the sum of the torque supplied by the thermal engine MT and that supplied by the electric machine ME.

[0004] It is therefore necessary that, whatever the torque required from the MT motor, the KO coupling can remain in the closed state (without slipping) and thus transmit the entire torque supplied by the MT motor to the MR electric machine and then to the wheel through the transmission.

[0005] However, in certain circumstances, it happens that the coupling system is in a degraded state leading to a drop in the maximum transmissible torque (denoted CMT). Thus, the coupling system can no longer transmit the entire torque of the MT thermal engine.

[0006] In this case, and when the thermal engine MT transmits more torque than the coupling KO can transmit (torque of the thermal engine MT greater than the maximum transmissible torque CMT), then the coupling KO slips and this results in: - heating of the clutch discs leading to an increase in energy consumption; - premature wear of the clutch discs; and - a variation in the speed of the thermal engine perceptible by the driver.

[0007] An objective of the present invention is to remedy the defects of the prior art, and in particular to propose a solution for limiting damage to the clutch disc, and improving driving comfort.

[0008] To achieve this objective, the invention proposes a motor vehicle comprising: - a heat engine; - a coupling means connected to the heat engine; - an electrical machine connected by means of coupling; - a clutch system connected to the electric machine; - a gearbox connected to the clutch system; - at least one axle connected to the gearbox; - a means of calculating the maximum transmissible torque for calculating a maximum torque transmissible by the clutch system corresponding to the maximum torque supplied by the thermal engine coupled to the electric machine in the current gear; - a maximum operating torque calculation means for calculating a maximum operating torque from the maximum transmissible torque and a transfer function minimizing the maximum transmissible torque; - a torque control means limiting the torque applied to the axle to the maximum operating torque.

[0009] Advantageously, the invention makes it possible to provide a margin between the maximum transmissible torque and the maximum torque actually applied so that in the event of a fault in the coupling means, there is no slippage thereof. Thus, the invention provides a safety margin which compensates for errors in the production of engine torque or the coupling system.

[0010] This results in a reduction in slippage of the coupling means and preservation of the clutch discs, as well as an optimization of energy consumption. Furthermore, there is no acoustic nuisance.

[0011] Preferably, the transfer function makes it possible to determine for each value of the maximum transmissible torque, a corresponding value of maximum operating torque.

[0012] This makes it possible to have operating torque values ​​parallel to the transmissible torque values.

[0013] Preferably, the transfer function is in the form of a mapping.

[0014] This makes it easy to determine the working torque values.

[0015] Preferably, the clutch system is a dual clutch system.

[0016] This makes it possible to adapt the invention to the applicant's E-DCT type dual clutch vehicles.

[0017] Preferably, said calculation means are implemented continuously or at several time intervals.

[0018] This makes it possible to adapt the value of the operating torques continuously or regularly.

[0019] The invention further relates to a method for controlling torque in a motor vehicle according to the invention, comprising the following steps: - a step of calculating the maximum transmissible torque in which a maximum torque transmissible by the clutch system corresponding to the maximum torque supplied by the thermal engine coupled to the electric machine in the current gear; - a maximum operating torque calculation step in which a maximum operating torque is calculated from the maximum transmissible torque and a transfer function minimizing the maximum transmissible torque; - a torque control step in which the torque applied to the axle is limited to the maximum operating torque.

[0020] Preferably, the transfer function makes it possible to determine for each value of the maximum transmissible torque, a corresponding value of maximum operating torque.

[0021] Preferably, said calculation steps are implemented continuously or at several time intervals.

[0022] Another object of the invention relates to a computer program comprising program code instructions for executing the steps of the torque control method according to the invention, when said program operates on a computer.

[0023] The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which: - [Fig.l] schematically illustrates a powertrain of a motor vehicle according to a preferred embodiment of the invention; - [Fig.2] schematically illustrates the steps of the control method according to the invention.

[0024] The invention is implemented in a vehicle comprising the elements illustrated in [Fig.l].

[0025] The motor vehicle comprises: - an MT thermal engine; - a KO coupling means connected to the MT thermal engine; - an electric machine ME connected by means of KO coupling; - a clutch system Kl, K2 connected to the electric machine ME; - a gearbox BV connected to the clutch system Kl, K2; - at least one axle R carrying wheels, connected to the gearbox BV.

[0026] The invention proposes to limit the setpoint torque of the engine by a maximum operating torque calculated from a maximum transmissible torque representative of the capacity of the coupling system to transmit torque coming from the thermal engine MT.

[0027] The maximum operating torque is calculated from the maximum torque transmissible by means of a parameterizable transfer function (for example a mapping).

[0028] The target torque requested from the MT thermal engine by the hybrid system in all circumstances is minimized by a maximum operating torque (noted CMF). This maximum operating torque is itself calculated directly from the maximum transmissible torque.

[0029] The transfer function makes it possible, for each value of the maximum transmissible torque, to determine an associated value of the maximum operating torque. This makes it possible to apply a safety margin which compensates for errors in the realization of the motor torque or the coupling system.

[0030] The maximum transmissible of the coupling system is calculated continuously in order to represent its capacity to transmit the torque of the MT thermal engine. It is representative of its operating state, nominal or degraded.

[0031] For example, in a nominal state, it will be able to transmit 400N.m, which is greater than the maximum torque achievable by the MT thermal engine (for example 300N.m). On the other hand, in a degraded state, it will only be able to transmit 200N.m maximum, which is less than the maximum torque of the MT thermal engine.

[0032] The invention further relates to a corresponding torque control method and program. The program can be loaded into the memory of a controller of the motor vehicle.

[0033] The torque control method is illustrated in [Fig.2].

[0034] This method comprises a step of calculating the maximum transmissible torque EL In this step, we calculate the maximum torque transmissible by the clutch Kl, K2 corresponding to the maximum torque supplied by the thermal engine coupled to the electric machine in the current gear.

[0035] The method further comprises a step of calculating the maximum operating torque E2. In this step, the maximum operating torque is calculated from the maximum transmissible torque and the transfer function minimizing the maximum transmissible torque.

[0036] The method further comprises a torque control step E3. In this step, the torque applied to the axle R is limited to the maximum operating torque.

Claims

Claims

1. Motor vehicle comprising: - a heat engine (MT); - a coupling means (KO) connected to the heat engine (MT); - an electric machine (ME) connected to the coupling means (KO); - a clutch system (Kl, K2) connected to the electric machine (ME); - a gearbox (BV) connected to the clutch system (Kl, K2); - at least one axle (R) connected to the gearbox (BV); - a maximum transmissible torque calculation means for calculating a maximum transmissible torque (CMT) by the clutch system (Kl, K2) corresponding to the maximum torque supplied by the heat engine (MT) coupled to the electric machine (ME) in the current gear; - a maximum operating torque calculation means for calculating a maximum operating torque (CMF) from the maximum transmissible torque (CMT) and a transfer function minimizing the maximum transmissible torque (CMT);- a torque control means limiting the torque applied to the axle (R) to the maximum operating torque (CMF).;

2. Motor vehicle according to claim 1, characterized in that the transfer function makes it possible to determine for each value of the maximum transmissible torque (CMT), a corresponding value of maximum operating torque (CMF).

3. Motor vehicle according to any one of claims 1 to 2, characterized in that the transfer function is in the form of a map.

4. Motor vehicle according to any one of claims 1 to 3, characterized in that the clutch system is a dual clutch system.

5. Motor vehicle according to any one of claims 1 to 4, characterized in that said calculation means are implemented continuously or at several time intervals.

6. Method for controlling torque in a motor vehicle according to any one of claims 1 to 5, comprising the following steps: - a step of calculating the maximum transmissible torque (El) in which a maximum transmissible torque (CMT) is calculated by the clutch system (Kl, K2) corresponding to the maximum torque supplied by the thermal engine (MT) coupled to the electric machine (ME) on the current gear; - a maximum operating torque calculation step (E2) in which a maximum operating torque (CMF) is calculated from the maximum transmissible torque (CMT) and a transfer function minimizing the maximum transmissible torque (CMT); - a torque control step (E3) in which the torque applied to the axle (R) is limited to the maximum operating torque (CMF).

7. Torque control method according to claim 6, characterized in that the transfer function makes it possible to determine for each value of the maximum transmissible torque (CMT), a corresponding value of maximum operating torque (CMF).

8. Torque control method according to any one of claims 6 to 7, characterized in that said calculation steps are implemented continuously or at several time intervals.

9. A computer program comprising program code instructions for performing the steps of the torque control method according to any one of claims 6 to 8, when said program is running on a computer.

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