FR3109337A1 - PROCESS FOR DRIVING THE TORQUE PRODUCED ON THE PRIMARY SHAFT OF A HYBRID MOTOR VEHICLE POWERTRAIN GROUP - Google Patents

Abstract

The invention relates to a method for controlling the torque produced on the primary shaft of a powertrain of a hybrid motor vehicle, said method comprising the following steps: a step of obtaining (101) a target function defining a torque at produce on the primary shaft at all times; - a step of obtaining (102) an affine function defining a torque to be produced by said heat engine at each instant; - a step of determining (103) a compensation function defining a torque to be produced by said electric motor at each instant; - a step of producing (104) a real torque by said heat engine at each instant based on said affine function; - a step of producing (105) an actual torque by said electric motor based on said compensation function in order to control the torque produced on said primary shaft. Fig. 1

Description

METHOD FOR CONTROLLING THE TORQUE PRODUCED ON THE PRIMARY SHAFT OF A HYBRID MOTOR VEHICLE POWERTRAIN

The invention relates to a method for controlling the torque produced on the primary shaft of a powertrain. The invention also relates to a control device capable of implementing the method according to the invention.

It is known from the prior art of motor vehicles called hybrid vehicles because it generally comprises two engines. Hybrid vehicles are known comprising a heat engine, of the gasoline or diesel type, and an electric motor. The thermal engine and the electric motor are connected by means of a primary shaft via a clutch and a gearbox. The heat engine produces a first torque and the electric motor produces a second torque. When the clutch is closed, these first and second torques add up and are then transmitted to the wheels of the hybrid vehicle via the primary shaft. Known from the state of the art is document EP 2 055 567 B1 which discloses a method for controlling a motor coupled to an input element of a hybrid transmission, the hybrid transmission having the function of transferring power between the motor and a second torque machine and an output element, the method comprising the step of monitoring a torque request from an operator, the step of controlling operation of the hybrid transmission in an operating range state continuously variable, a step of determining engine commands comprising a first engine torque request and a second engine torque request on the basis of the torque request from the operator and the operation of the hybrid transmission, a step determining an engine torque constraint comprising a maximum engine torque based on an ability of the hybrid transmission to react to the engine torque and a step of controlling the function nmenting the motor based on the first motor torque request only when the second motor torque request exceeds the motor torque constraint. The main drawback of the solution disclosed in the state of the art is that the heat engine can present strong torque variations. The electric motor is supposed to compensate for these variations in torque, but, in practice, there are jerks and shocks when driving the hybrid vehicle. Indeed, the various computers responsible for determining the torque to be produced by the electric motor have relatively long response times. Consequently, the torque compensation generated by the electric motor is not in agreement with the torque produced by the heat engine. The driver of the vehicle then feels various inconveniences, such as jolts.

The object of the invention is therefore to overcome the drawbacks of the prior art by proposing a method, and a device, for controlling the torque produced on the primary shaft of the powertrain of the hybrid motor vehicle making it possible to reduce the jolts and shocks during transient states such as a deceleration phase then an acceleration phase or an acceleration phase then a deceleration phase.

To do this, the invention thus relates, in its broadest sense, to a method for controlling the torque produced on the primary shaft of a hybrid motor vehicle powertrain, said powertrain comprising a heat engine and a electric motor mounted in series on said primary shaft, said method comprising the following steps:

- a step for obtaining a target function defining a torque to be produced on the primary shaft at each instant;

- a step of obtaining an affine function defining a torque to be produced by said heat engine at each instant;

- a step of determining a compensation function defining a torque to be produced by said electric motor at each instant, said torque being equal to the difference between said torque to be produced on the primary shaft at each instant according to said target function and said torque to be produced by said heat engine at each instant according to said affine function;

- a step of producing a real torque by said heat engine at each instant based on said affine function;

- a step of producing a real torque by said electric motor based on said compensation function in order to control the torque produced on said primary shaft.

Preferably, said affine function decreases or increases, respectively, during deceleration or acceleration of said hybrid motor vehicle.

According to an advantageous characteristic, said affine function comprises a slope of between -100 Nm/s and -250 Nm/s or between +100 Nm/s and +250 Nm/s, respectively, during deceleration or acceleration of said hybrid motor vehicle.

Preferably, said compensation function is determined so as to produce a substantially constant torque on said primary shaft of between +25 Nm and -25 Nm for a predetermined period of time.

In a preferred mode, said time period is between 0.1 and 0.6 s.

Advantageously, said period of time is approximately equal to 0.2 s.

The invention also relates to a device for controlling the torque produced on the primary shaft of a hybrid motor vehicle powertrain, said powertrain comprising a heat engine and an electric motor mounted in series on said primary shaft, characterized in that said device is intended to implement the steps of the method according to the invention, said device comprising a member for obtaining a target function defining the torque to be produced on the primary shaft at each instant, a member for obtaining a affine function defining the torque to be produced by said heat engine at each instant, means for determining a compensation function defining said torque to be produced by said electric motor at each instant, said torque being equal to the difference between the torque to be produced on the primary shaft at each instant according to said target function and said torque to be produced by said heat engine at each instant according to n said affine function, said heat engine being configured to produce a real torque at each instant based on said affine function and said electric motor being configured to produce a real torque based on said compensation function in order to control the torque produced on said primary shaft .

The invention further relates to a data processing system comprising a processor configured to implement the steps of the method according to the invention.

The invention also relates to a product of the computer program type, comprising at least one sequence of instructions stored and readable by a processor and which, once read by this processor, causes the steps of the method to be carried out according to the invention.

The invention further relates to a computer-readable medium comprising said computer program product.

Several embodiments of the present invention will be described below, by way of non-limiting examples, with reference to the appended figures in which:

illustrates a block diagram of the method according to one embodiment of the invention;

graphically represents, in one embodiment of the invention, the torques produced by a combustion engine and an electric motor of a hybrid motor vehicle and the torque produced on the primary shaft of said hybrid motor vehicle when the method according to the invention is implemented.

Referring to Figure 1, there is shown a block diagram of the method according to the invention. The method is intended to be implemented on a hybrid motor vehicle comprising a powertrain having a heat engine, such as a gasoline or diesel engine, and an electric motor. The thermal and electric motors are connected to the same power transmission shaft called the primary shaft. The powertrain also includes a clutch disposed between the heat engine and the electric motor. A gearbox is directly connected to the electric motor. When the clutch is closed, the torque produced by the heat engine and the torque produced by the electric motor add up and are transmitted to the primary shaft. The total torque available on the primary shaft is transmitted to the wheels of the hybrid motor vehicle. The method according to the invention makes it possible to control the torque produced on the primary shaft. This method firstly comprises a step 101 for obtaining a target function 3a defining the torque to be produced on the primary shaft at each instant t. Referring to Figure 2, there is shown a particular embodiment of the present invention in the form of a graph representing the torque in Nm as a function of time t. It is represented by a thick dashed line the target function 3a. The target function 3a has three parts. A first part starting from the point 200 Nm and 0 s to end around -25Nm and 0.5 s. This is the deceleration of the hybrid motor vehicle. The target function 3a then has a second part 4 at a substantially constant torque, namely -25 Nm, for about 0.2 s and finally a third part starting around the point -25 Nm and 0.7 s and ending around from the point -125 Nm and 0.9 s. The second part of the target function 3a makes it possible, during the transition phase between the deceleration and the acceleration of the hybrid motor vehicle, to avoid shocks in the gearbox. In fact, there are operating clearances in the gearbox between its gears and during changes in the direction of rotation thereof, these clearances are taken up. The method according to the invention has the advantage of substantially limiting these shocks. The method then continues with a step 102 for obtaining an affine function 2a defining the torque to be produced by the heat engine at each instant t. Referring to Figure 2, the affine function 2a is shown in thick dotted line. It has a slope of about -200 Nm/s. The method then includes a step 103 for determining a compensation function 1a, shown in thin dashed line in FIG. 2, defining the torque to be produced by the electric motor at each instant t. This torque is equal to the difference between the torque to be produced on the primary shaft at each instant t according to the target function 3a and the torque to be produced by the heat engine at each instant t according to the affine function 2a. According to a production step 104, a torque is actually produced by the heat engine at each instant t based on the affine function 2a. The production of this torque 2b is represented graphically by a thick dotted line in FIG. 2. The method then comprises a step 105 of producing a torque by the electric motor based on the compensation function 1a in order to control the torque produced on the primary shaft. The production of this torque 1b is represented graphically by a thin line in FIG. 2. The advantage of implementing an affine function 2a for the production of a torque by the heat engine is that the electric motor can easily produce a torque compensation, even if there is a production delay for this couple. In this way, shocks and jolts are significantly reduced, or even virtually non-existent. In a particular embodiment, the affine function 2a decreases during deceleration of the hybrid motor vehicle, with a slope of between -100 Nm/s and -250 Nm/s, and preferably equal to about -200 Nm/ s. In another particular embodiment of the invention, the affine function increases with a slope between +100 Nm/s and +250 Nm/s, and preferably equal to about +200 Nm/s. Alternatively, the compensation function 1a is determined so as to produce a substantially constant torque on the primary shaft of between +25Nm and – 25Nm for a predetermined period of time. The compensation function 1a is determined when carrying out tests, as well as the predetermined time period. In a particular embodiment, this time period is between 0.1 and 0.6 s. This period of time is predetermined so as to be large enough to avoid the generation of shocks and jolts while providing good driving pleasure for the driver of the hybrid motor vehicle. Preferably, this time period is about 0.2 s. Thus, the transition between a deceleration phase and an acceleration phase or between an acceleration phase and a deceleration phase is fast enough that the driver does not feel it. With reference to FIG. 2, the torque actually produced by the heat engine is represented by graph 2b, in dotted line. As for the torque actually produced by the electric motor, this is represented by graph 1b in a thin continuous line. The torque actually produced on the primary shaft is represented by graph 3b in bold dashed lines.

The invention also relates to a device for controlling the torque produced on the primary shaft of the powertrain of the hybrid motor vehicle. The device comprises a member for obtaining the target function, such as a computer or a supervisor, a member for obtaining the affine function 2a, such as another computer or the same supervisor. The device further comprises a means for determining the compensation function 1a. In a particular mode, this means is the supervisor of the hybrid motor vehicle in which the compensation calculation is performed. The heat engine is configured to produce a torque at each instant t based on said affine function 2a and the electric motor is configured to produce a torque based on said compensation function 1a in order to control the torque produced on the primary shaft.

In a particular embodiment, the method according to the invention implements a computer, such as a supervisor or a computer. The present invention can be implemented by means of a data processing system comprising a processor configured to implement all the steps of the method. In addition, a product of computer program type comprising at least one sequence of instructions stored and readable by a processor and which, once read by this processor, causes the steps of the method according to the invention to be carried out. A computer readable medium includes said computer program product.

Claims (10)

Method for controlling the torque produced on the primary shaft of a hybrid motor vehicle powertrain, said powertrain comprising a heat engine and an electric motor mounted in series on said primary shaft, said method comprising the following steps:
- a step of obtaining (101) a target function (3a) defining a torque to be produced on the primary shaft at each instant (t);
- a step of obtaining (102) an affine function (2a) defining a torque to be produced by said heat engine at each instant (t);
- a step of determining (103) a compensation function (1a) defining a torque to be produced by said electric motor at each instant (t), said torque being equal to the difference between said torque to be produced on the primary shaft at each instant (t) according to said target function (3a) and said torque to be produced by said heat engine at each instant (t) according to said affine function (2a);
- a step of production (104) of a real torque by said heat engine at each instant (t) based on said affine function (2a);
- a step of producing (105) a real torque by said electric motor based on said compensation function (1a) in order to control the torque produced on said primary shaft. Method according to Claim 1, characterized in that the said affine function (2a) decreases or increases, respectively, during a deceleration or an acceleration of the said hybrid motor vehicle. Method according to Claim 2, characterized in that the said affine function (2a) comprises a slope of between -100 Nm/s and -250 Nm/s or between +100 Nm/s and +250 Nm/s, respectively, during deceleration or acceleration of said hybrid motor vehicle. Method according to any one of Claims 1 to 3, characterized in that the said compensation function (1a) is determined so as to produce a substantially constant torque on the said primary shaft of between +25 Nm and -25 Nm for a period of time predetermined. Method according to Claim 4, characterized in that the said period of time is between 0.1 and 0.6 s. Method according to Claim 5, characterized in that the said period of time is approximately equal to 0.2 s. Device for controlling the torque produced on the primary shaft of a hybrid motor vehicle powertrain, said powertrain comprising a heat engine and an electric motor mounted in series on said primary shaft, characterized in that said device is intended to implement the steps of the method according to any one of claims 1 to 6, said device comprising a member for obtaining a target function (3a) defining a torque to be produced on the primary shaft at each instant (t), a member for obtaining an affine function (2a) defining a torque to be produced by said heat engine at each instant (t), means for determining a compensation function (1a) defining a torque to be produced by said electric motor at each instant (t), said torque being equal to the difference between said torque to be produced on the primary shaft at each instant (t) according to said target function (3a) and said torque to be produced by said motor r thermal at each instant (t) according to said affine function (2a), said heat engine being configured to produce an actual torque at each instant (t) based on said affine function (2a) and said electric motor being configured to produce a torque real based on said compensation function (1a) in order to control the torque produced on said primary shaft. A data processing system comprising a processor configured to implement the steps of the method according to any one of claims 1 to 6. Product of the computer program type, comprising at least one sequence of instructions stored and readable by a processor and which, once read by this processor, causes the steps of the method according to any one of Claims 1 to 6 to be carried out. A computer-readable medium comprising said computer program product according to claim 9.