FR3034471A1 - SYSTEM FOR A MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a system (1) for a motor vehicle, this system comprising: - a reversible electric machine (2) configured to be able to produce an electric current when the machine is operating as an alternator, and participate in starting an internal combustion engine (3) of the vehicle when this machine operates as a motor, - a starter (4) to start the internal combustion engine of the vehicle after an automatic stop phase for the first compressions of the combustion engine, before the reversible machine takes over for the following compressions including an idle speed.

Description

The present invention relates to a system for a motor vehicle, in particular a truck or a bus. The invention aims in particular to allow an automatic start function, or also called Stop-Start, on a truck or a bus. In the context of trucks or buses, it is more difficult to perform the Stop-Start function, in particular because it is necessary to produce large torques to initiate the rotation of the internal combustion engine. In addition, if a reversible electric machine is used to drive the combustion engine via a belt, when automatically starting, the belt can slide, which is undesirable. The invention aims in particular to overcome this type of difficulty. The invention thus relates to a system for a motor vehicle, this system comprising: a reversible electric machine configured to be able to produce an electric current when the machine is operating as an alternator, and participate in starting the internal combustion engine of the vehicle when this machine operates as a motor, 25 a starter to start the internal combustion engine of the vehicle after an automatic stop phase, also called ldling Stop in English, for the first compressions of the engine, before the machine reversible take over for the following compressions including up to idle speed. Thanks to the invention, it is possible to reduce the load on the starter in the automatic restart phase because the electric machine takes over, which preserves the life of the starter.

In addition, the invention allows a faster revving and thus reduce the restart time. In addition, the invention makes it possible to postpone the start of the injection in order to achieve fuel savings. The invention also makes it possible to reduce the pollutants in the engine restart phase. The automatic stop phase corresponds for example to a stop at a red light, and the combustion engine is restarted when the driver presses the accelerator pedal or clutch. The machine may be a synchronous rotating electrical machine with double excitation, that is to say having a rotor provided with permanent magnets and an excitation winding. Advantageously, the starter is arranged to be able to start the cold combustion engine, in addition to contributing to the automatic restart of the combustion engine. This type of starter is still called a reinforced starter. For example, this type of starter is capable of performing approximately 300,000 startup / restart cycles. The starter preferably comprises a pinion arranged to cooperate with a flywheel of the combustion engine.

The starter is for example permanently meshing with a flywheel of the combustion engine. In an exemplary implementation of the invention, the reversible electric machine is arranged to cooperate with the combustion engine via a transmission belt. Thanks to the invention, when the reversible machine takes over after the starter, the efforts to develop by the reversible machine are less so as to limit the risk of slippage of the belt. The reversible electric machine comprises in particular a pulley arranged to cooperate with the transmission belt.

The electric machine has in particular an electrical power of between 4 and 25 KWatts, in particular between 6 and 12 KWatts, in particular a power substantially equal to 8 KWatts. The electric machine is, if desired, configured to generate electric current during braking of the vehicle engine. This allows regenerative braking. If necessary, the electric machine is configured to assist the combustion engine when the latter is in operation. The starter is advantageously arranged to drive the combustion engine to a threshold speed of rotation of the engine, in particular 50 revolutions / minute, and then, once the rotation of a crankshaft of the engine is started, the reversible electric machine takes the relay to allow the revving of the engine to idle speed. The invention also relates to a method for starting an internal combustion engine at the end of an automatic stopping phase, the method comprising the following steps: - rotating a crankshaft of the combustion engine using of a starter, - Once the rotation of the crankshaft has begun, use a reversible electric machine to allow the revving of the combustion engine in particular to an idle speed. The process may include the following step: - When the idle speed is reached, proceed to the injection of fuel to the combustion engine.

The invention is particularly advantageous for a truck or a bus. The invention will be better understood and other details, features and advantages of the invention will become apparent on reading the following description given by way of nonlimiting example with reference to the appended drawing in which: FIG. schematic and partial view of a system according to an exemplary embodiment of the invention, - Figures 2 and 3 illustrate the evolution of the rotational speed of the combustion engine as a function of time, respectively according to an operation using only a starter, and according to an operation according to the invention, and - Figure 4 is a block diagram illustrating the operation of the system of Figure 1. There is shown in Figure 1 a system 1 for a motor vehicle, the system comprising: a reversible electric machine 2 configured to be able to produce an electric current when this machine is operating as an alternator, and to participate in starting a combustion engine 3 of the vehicle when the machine 2 is operating as an electric motor, - a starter 4 for starting the internal combustion engine 3 of the vehicle after an automatic stopping phase, for the first compressions of the heat engine 3, before the reversible machine 2 takes over for subsequent compressions to idle speed.

In the example described, the machine 2 is a synchronous rotating electrical machine with double excitation, that is to say having a rotor provided with permanent magnets and an excitation winding. When the machine 2 is operating as an alternator, this machine 25 makes it possible to recharge a battery of an electrical architecture 5 of the vehicle. This architecture 5 may or may not include a DC / DC converter. The reversible electric machine 2 is arranged to cooperate with the combustion engine 3 via a transmission belt 10.

The electric machine 2 comprises for this purpose a pulley 11 arranged to cooperate with the transmission belt 10. The combustion engine 3 comprises a crankshaft 14 which cooperates with the belt 10 so that the engine 3 can be selectively driven by the machine 2 or train this machine 2.

The electric machine 2 has an electric power of between 4 and 25 KWatts. The machine 2 has an integrated power electronics. Alternatively, this power electronics can be deported. The electric machine 2 is configured to generate electric current when braking the vehicle engine. This allows regenerative braking. If necessary, the electric machine is configured to assist the combustion engine when the latter is in operation. The vehicle is a truck or a bus. For example, such a vehicle weighs at least 7 tons and / or has a heat engine of at least 4L displacement. The automatic stopping phase corresponds for example to a stop at a red light, and the combustion engine 3 is restarted automatically when the driver presses the accelerator pedal 30 or clutch.

The starter 4 is arranged to be able to start the combustion engine 3 cold, in addition to contributing to the automatic restart of the combustion engine. This type of starter is still called a reinforced starter. For example, this type of starter is capable of achieving 300,000 startup / restart cycles. The starter 4 comprises a pinion 7 arranged to cooperate with a flywheel 8 of the combustion engine 3. The starter 4 is, in the example described, in permanent engagement with the flywheel 8 of the combustion engine via the pinion 7.

Other types of starter can of course be used in place of the permanent meshing type. In the example described, the reversible electric machine 2 and the electric starter 4 electrically connected to the electrical architecture 5 are coupled to the heat engine 3 respectively on two opposite faces of the engine. Thus one of the couplings is on the front face of the engine 3 and the other of the couplings is on the rear face of the engine 3. The starter 4 is arranged to drive the combustion engine 3 up to a speed threshold of rotation of the engine 3, in the example described 50 rpm, and then, once the crankshaft 14 of the engine is started to rotate, the reversible electric machine 2 takes over to allow the engine to ramp up to its idle speed . Thus the system 1 operates as follows: 25 - Rotate the crankshaft 14 of the combustion engine 3 with the starter 4, the machine 2 being stopped until the crankshaft 14 begins to rotate (phase 1 of FIG. 3, step 30 of FIG. 4), - once the rotation of the crankshaft 14 has begun, use the reversible electric machine 2 to allow the combustion engine 3 to ramp up to an idling speed R as the starter 4 is no longer biased (phase 2 of FIG. 3, step 31 of FIG. 4), when the idle speed R is reached, proceed with the injection of fuel towards the combustion engine 3 (phase 3 of Figure 3, step 32 of Figure 4). Compared to operation without a reversible machine and only with a starter for starting, as illustrated in FIG. 2, the phase 1 which uses the starter is shortened in time thanks to the invention, and advantageously the beginning of the fuel injection. is repelled, which reduces consumption and pollutant emissions. In addition, the starter 4 in the invention is biased to a speed threshold Si that is lower than a threshold S2 in the case of a starter-only start. The invention thus makes it possible to reduce the stresses on the starter 4.

Claims (9)

REVENDICATIONS1. System (1) for a motor vehicle, this system comprising: - a reversible electric machine (2) configured to be able to produce an electric current when this machine is operating as an alternator, and participate in starting an internal combustion engine (3) of the vehicle when this machine operates as a motor, - a starter (4) to start the internal combustion engine of the vehicle after an automatic stop phase for the first compressions of the combustion engine, before the reversible machine takes the relay for subsequent compressions including up to idle speed. 2. System according to the preceding claim, the starter (4) being arranged to be able to start the cold combustion engine. 3. System according to one of the preceding claims, the starter comprises a pinion (7) arranged to cooperate with a wheel (8) of the combustion engine. 4. System according to one of the preceding claims, the reversible electric machine (2) is arranged to cooperate with the combustion engine (3) via a transmission belt (10). 3034471 5. System according to rune preceding claims, the reversible electric machine (2) comprises a pulley (11) arranged to cooperate with the transmission belt (10). 5 6. System according to one of the preceding claims, the electric machine (2) having an electric power of between 4 and 25 KWatts, in particular between 6 and 12} <Watts, including a power substantially equal to 8 '<Watts. 10 7. System according to one of the preceding claims, the starter (4) is arranged to drive the combustion engine to a threshold speed of rotation of the engine, in particular 50 revolutions / minute, and then, once the rotation With a crankshaft of the engine primed, the reversible electric machine takes over to allow the engine to ramp up in particular to its idle speed (R). 8. A method for starting an internal combustion engine after an automatic stopping phase, the method comprising the following steps: - rotating a crankshaft of the combustion engine with a starter, Once the rotation of the crankshaft has begun, use a reversible electric machine to allow the revving of the combustion engine including an idle speed. 9. Method according to the preceding claim, comprising the following step: - When the idle speed is reached, proceed to the injection of fuel to the engine.