FR3024752A1 - METHOD FOR MANAGING THE OPERATION OF A THERMAL MOTOR OF A HYBRID VEHICLE - Google Patents

Abstract

The invention relates to a method for managing the operation of a heat engine (2) of a hybrid vehicle during a torque request, said engine (2) being supercharged by means of a turbocharger (11) whose at least the turbine (14) or the compressor (12) is of variable geometry and comprises fins (16) orientable and able to be moved between an open position for which they promote the passage of gases and a closed position for which they offer maximum resistance to said gases. The main characteristic of a management method according to the invention is that it comprises the following steps, - a step of request (22) torque by the driver and that the electric motor (15) is not able to provide all alone, - a step of maneuvering (24) the fins by means of a control device (19) to place them in a closed position, as soon as said torque request has been initiated, - a step starting (26) of the heat engine (2), once said fins (16) have been placed in said closed position.

Description

FIELD OF THE INVENTION The invention relates to a method for managing the operation of a heat engine of a hybrid vehicle. As a reminder, a hybrid vehicle comprises an electric motor and a heat engine, said engine being in addition to the electric motor on certain sectors of a road course. During a driving phase of a hybrid vehicle, provided only by the electric motor, it happens that the driver of said vehicle requires an increase in torque, which can not be provided by the single electric motor. To respond to this request, it must solicit the engine, restarting it and then bringing it to a regime and a target load corresponding to its torque demand. However, generally, the response time of the engine to achieve the desired result, is important, forcing the driver to wait a long time, before seeing his vehicle respond to the solicitation requested. This time lag between the control command and the engine reaction is poorly perceived by the driver, who has the impression that his vehicle reacts to a delay. In the case of supercharged engines, this quick start is not possible without intervention on the supercharging system. For example, the European patent application EP0367406 describes a vehicle comprising a heat engine, associated with a turbocharger equipped with an electric machine. Thus, when starting the heat engine, the electric machine is actuated to increase the acceleration of the turbocharger, which is then able to provide the desired torque. This configuration however has the disadvantage of requiring the presence of an additional motor to operate the turbocharger to provide the requested torque. Another means of accelerating a fixed geometry turbocharger would be to design a turbine of smaller inertia. But 3024752 2 with a smaller turbine, it would not be possible to keep the engine performance at high speed. A method of managing the operation of a heat engine of a hybrid vehicle according to the invention, allows said engine to instantly provide the required performance in terms of torque, without the addition of additional parts, and without having to resize in depth the turbocharger. The subject of the invention is a method of managing the operation of a heat engine of a hybrid vehicle during a torque request, said engine being supercharged by means of a turbocharger, of which at least the turbine or the compressor is variable geometry, and comprises orientable fins and able to be moved between an open position for which they promote the passage of gases and a closed position for which they offer maximum resistance to said gases.

The main characteristic of a method according to the invention is that it comprises the following steps, a torque request step by the driver and that the electric motor is not able to provide on its own, a step actuating the fins by means of a control device to place them in a closed position, as soon as said torque request has been initiated, a starting step of the engine, once said fins have been placed in said position closure. It is assumed that a hybrid vehicle comprises an electric motor and a heat engine, and that a turbocharger comprises a turbine coupled to a compressor. Thus, according to such a management method, the driver makes a request for torque, whether the vehicle is stopped or in the rolling phase. The steerable vanes of the compressor and / or turbine, are then instantly placed in a closed position so as to have the maximum resistance to gas passage. In this way, the heat engine associated with the turbocharger geometry 3024752 3 variable, reacts in real time to this torque demand, thus erasing the delays in operation, glimpsed with the architectures of existing supercharged hybrid vehicles. Preferably, the fins are rotatable to move from the open position to the closed position.

Orientable vanes may be implanted either in the compressor or in the turbine, or both in said compressor and said turbine. It is indeed assumed that the electric motor of the hybrid vehicle, is not able to provide all alone, the torque demand requested by the driver, and therefore that the heat engine must be obligatorily 10 solicited for this service. The control device is autonomous and can be controlled independently of the state of the engine and the electric motor. Advantageously, the orientable fins are implanted only in the turbine.

According to a preferred embodiment of a management method according to the invention, the control device is a pneumatic device comprising a vacuum reserve. Preferably, the vacuum reserve is achieved by means of an electric vacuum pump, capable of operating during the rolling phase of the vehicle. In this way, the vacuum is created while the hybrid vehicle is in rolling phase. According to another preferred embodiment of a management method according to the invention, the control device is an electrical device comprising a secondary electric motor and an operating rod, said electric motor moving the rod to actuate the movement mechanism. fins. Advantageously, the secondary electric motor is adapted to be rotated to move the operating rod. Other types of electrical devices are possible. For example, a solenoid can be used to move the rod so as to actuate the fin moving mechanism.

Preferably, an operating method according to the invention comprises a safety step of automatically replacing the fins in an open position, in the event of a failure of the control device, after the fins have been removed. placed in a closed position. Indeed, during a torque request by the driver, the fins are instantly placed in a closed position. This demand for torque is generally limited in time to meet a specific need. However, if the control device fails, the fins may tend to remain frozen in their closed position, inadvertently lengthening the acceleration phase of the engine, and increasing the potential risk of accident. The safety step tends to reduce by default, the adjustable fins in their open position. Advantageously, the safety step is carried out by means of a prestressed spring device making it possible to replace the fins in their open position. It is assumed that the control device must first overcome the forces generated by the prestressed spring, to be able to place the fins in a closed position. In the event of a failure of said control device once said fins have been placed in this closed position, the spring returns said fins to an open position, attempting to regain its relaxation position. Preferably, an operating method according to the invention is controlled by an onboard computer. Indeed, the computer receives the torque request, then instantly transmits a signal to the control device to place the fins in a closed position. The engine can then start once said fins have reached this closed position. When the torque demand ceases, the computer sends a deactivation signal to the control device to replace the fins in an open position. This replacement can be effected either actively by means of a specific motor organ specially designed for this replacement, or passively by means of a return means operative once the command has been disabled. The object of the invention is a drive element of a hybrid vehicle for implementing a method according to the invention, said element comprising a heat engine, and a turbocharger, of which at least the turbine or the The compressor is of variable geometry and comprises blades that are orientable and able to be displaced between an open position for which they promote the passage of gases and a closed position for which they offer maximum resistance to said gases. The main characteristic of a motorization element according to the invention is that it comprises a control device that can be triggered during a torque request, to place the fins in a closed position for which they offer maximum strength. to gases. It is assumed that the control device is activated via an onboard computer capable of managing the operation of the engine and the turbocharger. A method of managing the operation of a heat engine of a hybrid vehicle according to the invention has the advantage of not requiring any additional bulky piece, which may weigh down the vehicle and take up too much space in the vehicle. vehicle. It also has the advantage of allowing the engine to respond reliably, reproducibly and rigorously to a torque demand from the driver, since the operating characteristics of a variable geometry turbocharger are known and well known. mastered. The following is a detailed description of a preferred embodiment of a method for managing the operation of a heat engine of a hybrid vehicle according to the invention and a drive element of a hybrid vehicle. allowing the implementation of such a method, with reference to Figures 1 to 4.

FIG. 1 is a schematic view of a drive element of a hybrid vehicle according to the invention; FIG. 2A is a schematic figure of a turbine with variable geometry, for which the fins are in the closed position, FIG. 2B is a schematic figure of a variable geometry turbine, for which the vanes are in the open position, FIG. 3 is a logic diagram showing the main steps of a management method according to the invention, FIG. 4 is a diagram illustrating an example of a regime 10 provided by a heat engine of a hybrid vehicle as a function of time, with a management method according to the invention. Referring to Figure 1, a drive element 1 of a hybrid vehicle according to the invention comprises an electric motor 15 and a supercharged engine 2, such as a diesel engine 15 having four cylinders in line. The hybrid vehicle operates mainly with the electric motor 15, the heat engine 2 supplementing the electric motor 15 during certain driving phases of said vehicle. For its operation, such a heat engine 2 draws air 20 in the direction of the arrow F1 through an intake line 3, and rejects its combustion gases in an exhaust line 4 in order to evacuate them to the outside atmosphere in the direction of arrow F2. The thermal engine 2 also consumes fuel, for example diesel fuel, which is supplied to said engine 2 by means of an injection system 25 (not shown), for example a direct injection system which includes a feed ramp at very high temperatures. high pressure common to the cylinders and at least one fuel injector per cylinder adapted to inject the fuel directly into each of the cylinders. The air intake line 3 comprises an air filter 5, a flow meter 6 30 for determining the mass flow rate of fresh air admitted into the engine 2, an air intake flap 7 for regulating the flow rate. admitted in the 3024752 7 engine 2 and an air intake manifold 8, or distributor 8, bringing the air passing through the intake flap 7 in the different cylinders of the engine 2. The exhaust line 4 comprises a collector 9, and at least one aftertreatment device 10 of the combustion gases of the engine, for example an oxidation catalyst 10, a particulate filter 10, a nitrogen oxide trap 10 or a catalyst of selective reduction of nitrogen oxides 10. The thermal engine 2 is supercharged, it also comprises a turbocharger 11, a compressor 12 is interposed in the intake line 3 between the flow meter 6 and the inlet flap 7. A heat exchanger of temperature 13 is disposed in the line of admissibility 3, between the compressor 12 and the inlet flap 7, so as to cool the compressed air by the compressor 12. The compressor 12 is driven by a turbine 14 of the turbocharger 11, which is interposed in the exhaust line 4, between the engine 2 and the after-treatment device 10. Conventionally, the exhaust line 4 is provided with a bypass line (not shown) which bypasses the turbine 14 and which has a discharge valve at exhaust, also called "waste gate" valve, to be able to limit the energy provided by the exhaust gas to the turbine 14, and therefore to limit the pressure supplied by the compressor 12.

The heat engine 2 may comprise one or more exhaust gas recirculation circuits at the inlet (not shown), more particularly a high pressure EGR (Exhaust Gas Recirculation) circuit and / or an EGR circuit. low pressure. With reference to FIGS. 2A and 2B, the turbine 14 has a variable geometry and comprises orientable vanes 16 and able to move between a closed position illustrated in FIG. 2A, and an open position illustrated in FIG. 2B. . The fins 16 are disposed along an annular portion 17 of the turbine 14, and are each rotatably mounted around an axis 18 emerging perpendicularly from said annular portion 17. A control device 19 comprising a secondary electric motor 20 and a rigid actuating rod 21 makes it possible to move in rotation and simultaneously, all the fins 16 of said turbine 3024752 8 14. The secondary electric motor 20 thus causes the displacement of the rod 21, which, by means of an element of transmission (not visible in the figures), transmits a rotational movement to each axis 18 on which is mounted a fin 16. Thus, by triggering the secondary electric motor 20, the fins 16 move simultaneously in rotation on the turbine 14. When the fins 16 are in an open position, as shown in Figure 2B, they tend to let through the exhaust easily. Conversely, when they are placed in a closed position, as illustrated in FIG. 2A, they have maximum resistance to these exhaust gases and cause instantaneous and rapid movement of the turbine 14, which accelerates the compressor 12. The fins 16 orientable are mounted on the turbine 14 by means of a spring device, allowing said fins 16 to be, by default, pushed into an open position. In this way, to place the vanes 16 in a closed position, the controller 19 must overcome the forces generated by said spring device. Referring to Figure 3, a method of managing the operation of a heat engine 2 of a drive element 1 according to the invention is controlled by a computer embedded in the hybrid vehicle. Such a method comprises the following steps, a torque request step 22 by the driver and which the electric motor 15 is not able to provide on its own. This torque demand can intervene, either when the vehicle is stopped or when it is in a rolling phase. This torque request is transmitted instantaneously to the computer. a pre-positioning step 23 of the secondary motor 20, so that it is operational to control the displacement of the orientable vanes 16. Indeed, once the torque demand reaches the computer, it sends a signal to the secondary electric motor 30 20 so that it positions itself in an operational configuration. - a step of maneuver 24 fins 16 of the secondary electric motor 20 to place them in a closed position, as soon as said torque request has been initiated. Indeed, once the secondary electric motor 20 has been pre-positioned, the computer controls said secondary motor 20 so that it places the fins 16 orientable in a closed position. a step of detecting the fins 16 in their closed position. - A starting step 26 of the engine 2. As the fins 16 have not reached this closed position, the engine 2 does not start. The management method according to the invention may, if necessary, include a waiting step 27, so that the fins 16 reach their closed position. As soon as they are properly placed in this position, the engine 2 starts. a step of raising the torque of the heat engine 2 to reach the desired speed. a repositioning step 29 of the fins 26 in an open position, as soon as the driver no longer wishes to request torque from the vehicle. Referring to Figure 4, a torque demand results in a setpoint regime 24 to be achieved by the engine 2, which is 2500rpm in the example shown. Thus, following this torque request, once the fins 16 of the turbine 14 have been placed in a closed position, the heat engine 2 starts, then slowly rises for about 1s as shown in the first part. 30 of the curve, the effect of the placement of the fins 16 in the closed position is not yet effective. The heat engine 2 then accelerates abruptly under the effect of the rapid movement of the turbine 14 caused by the placement of the fins 16 in a closed position, as illustrated by the second part 31 of the curve, to reach quickly the 3024752 2500tr / min speed set point. In this way, the heat engine 2 responds almost instantaneously to the torque demand of the driver, who notes with satisfaction that his vehicle reacts in real time to all the demands he submits to his engine 2. 5

Claims (10)

REVENDICATIONS1. Method for managing the operation of a heat engine (2) of a hybrid vehicle during a torque demand, said engine (2) being supercharged by means of a turbocharger (11), at least the turbine (14) of which or the compressor (12) is of variable geometry and comprises fins (16) which are orientable and able to be displaced between an open position for which they favor the passage of gases and a closed position for which they offer maximum resistance to said gas, characterized in that it comprises the following steps, a step of request (22) torque by the driver and that the electric motor (15) is not able to provide all alone, a maneuver step (24) fins by means of a control device (19) to place them in a closed position, as soon as said torque request has been initiated, a starting step (26) of the heat engine (2), a times that said fins (16) have been placed in said closed position. 2. Management method according to claim 1, characterized in that the orientable vanes (16) are implanted only in the turbine (14). 3. Management method according to any one of claims 1 or 2, characterized in that the control device (19) is a pneumatic device comprising a vacuum reserve. 4. Management method according to claim 3, characterized in that the vacuum reserve is achieved by means of an electric vacuum pump capable of operating during the driving phase of the vehicle. 5. Management method according to any one of claims 1 or 2, characterized in that the control device (19) is an electrical device comprising a secondary electric motor (20) and a rod (21) maneuvering, said electric motor (20) moving the rod (21) to actuate the fin moving mechanism (16). 6. Management method according to claim 5, characterized in that the secondary electric motor (20) is adapted to be rotated to move the rod (21) maneuvering. 7. Management method according to any one of claims 1 to 6, characterized in that it comprises a safety step of automatically replacing the fins (16) in an open position, in the case of a failure of the control device (19), after said fins (16) have been placed in a closed position. 8. Management process according to claim 7, characterized in that the safety step is performed by means of a prestressed spring device 15, to replace the fins (16) in their open position. 9. Management method according to any one of claims 1 to 8, characterized in that it is controlled by an onboard computer. 10.Element element (1) of a hybrid vehicle for carrying out a method according to any one of claims 1 to 9, said element (1) comprising a heat engine (2), and a turbocharger (11) of which at least the turbine (14) or the compressor (12) is of variable geometry and comprises fins (16) which are orientable and able to be displaced between an open position for which they promote the passage of gases and a closing position for which they provide maximum resistance to said gases, characterized in that it comprises a control device (19) adapted to be triggered during a torque request, for placing the fins (16) in a closing position for which they provide maximum gas resistance.