FR3040078A1 - METHOD FOR STARTING A VEHICLE INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

A method of starting an internal combustion engine (105) with a belt generator starter (130) and a pinion starter (110). The crankshaft (151) is connected in the torque transmission direction to the starter-generator (130) and the starter (110). The starter-generator (130) generates a biasing torque (Mvor1, Mvor2) applied to the crankshaft (151) in the direction opposite to the direction of rotation (152) of the crankshaft (151) and lower than the crankshaft launching torque (151) . The starter (110) alone or with the starter-generator (130) applies a starting torque to the crankshaft (151) at least equal to the starting torque of the crankshaft (151) which is set in motion.

Description

Field of the invention

The present invention relates to a method of starting an internal combustion engine of a motor vehicle as well as to a computing unit and a computer program for implementing the method.

State of the art

In the motor vehicle equipment, an electric machine is used in the form of a starter-generator for firstly starting the internal combustion engine by operating the electric machine in motor mode and secondly for generating the electric current. to power the on-board network and charge the vehicle battery by operating the electric machine in generator mode. The starters-generators are connected by a belt drive to the internal combustion engine, that is to say to the crankshaft of the engine.

Like belt starters (also called RSG starters) synchronous machines with rotating current and external excitation are particularly interesting because the motor torque is easy to adjust. The necessary torque can be adjusted by appropriately controlling the rotor winding (excitation coil) and / or winding of the stator (usually for example a three or five-phase stator). It may be advantageous to have a torque modulation so that the start is as quiet and vibration free as possible.

To start the internal combustion engine, the drive torque of the starter-generator is transmitted by the belt to the crankshaft of the internal combustion engine to accelerate the crankshaft to its minimum rotational speed and, when this speed of rotation is reached, the Flammable mixture is ignited at the determined moment in the combustion chamber.

To start the internal combustion engine, it must exceed the launch torque (start torque) which can be very important, especially for a cold start. Therefore, it is necessary to use powerful starters-generators. At very low temperatures, the starter-generator can reach its power limit. To avoid this situation, we can help the starter-generator or alternatively, use a starter gear, usual, especially for cold start.

Document DE 10 2012 203 374 A1 describes a method of prestressing the belt before starting and thus, the starter-generator gradually establishes and not suddenly the torque. The pinion starter is not used in this solution. Description and advantages of the invention

The present invention relates to a method for starting an internal combustion engine with a belt generator starter and a pinion starter, the internal combustion engine having a crankshaft capable of being connected in the direction of transmission of the torque. to the starter-generator belt and the starter gear, the starter generator belt generating a preload torque applied to the crankshaft which acts in the opposite direction to the direction of rotation of the crankshaft and which is lower than the crankshaft launch torque, the single-gear starter or pinion starter and belt starter-generator applying to the crankshaft a starting torque that is at least equal to the crankshaft starting torque and the crankshaft is set in motion by the starting torque.

In other words, the internal combustion engine comprises a starter-generator belt and a pinion starter. The pinion starter and the starter-generator can be installed in a common housing. When starting the internal combustion engine, the starter-belt generator provides a lower preload torque to the launch torque of the internal combustion engine. This prestressing torque is nevertheless sufficient to tension the belt with prestressing.

After application of belt pretension, sprocket start, single sprocket starter or in the case of a combination start, the sprocket starter and the belt starter-generator provide the starting torque. This starting torque is at least equal to the launch torque of the internal combustion engine. The starting torque is transmitted to the crankshaft of the internal combustion engine starts to spin and starts. After the launch, we can, if necessary, continue to increase the torque provided.

In principle, especially at warm start as in start / stop mode, the starting torque can be provided only by the starter-generator belt (this mode is called boot RSG).

The starter / generator belt is connected to the crankshaft of the internal combustion engine by a belt (for example a V-belt). This belt drive (auxiliary drive) can be connected not only to the starter-belt generator, but also to other components such as fans or cooling circuit pumps.

The pinion starter is an internal combustion engine starter, particularly in the form of an electric machine with an intermediate transmission with sun gear or spur gear and a disengaging device. The starter gear driven by the electric machine engages in the ring gear of the crankshaft of the internal combustion engine. When the pinion is sufficiently engaged in the ring gear, the rotor of the electric motor begins to rotate so that the starter gear transmits the torque to the internal combustion engine. It turns and starts.

There is also a tensioner for tensioning the belt, for example a pendulum tensioner or tensioner with two arms. The position of the belt tensioner or its pendular arms may vary in particular in the direction of the strand of the belt which will be stretched, that is to say shortened.

The prestressing torque thus generated does not rotate the internal combustion engine or the crankshaft, however. The prestressing torque thus generated ensures the prestressing of the drive belt, in this case, in particular the tension of the loaded strand according to the starting operation (hereinafter referred to as the starting load load).

The method minimizes the forces and stresses exerted on starting the internal combustion engine, on the belt and the components associated therewith as well as on the crankshaft. This increases the life of the starter-belt generator as well as the other components associated with the drive belt. In addition, the start is silently and comfortably thanks to the method of the invention.

When the internal combustion engine is at rest and no torque is applied to the drive belt, the belt and in particular the belt tensioner are in the rest position. The loaded and unloaded belts of the belts are at the same tension to the engine operating mode of the RSG starter generator. In the case of a usual sprocket start, when the sprocket starter applies torque to the crankshaft and the crankshaft starts to move, the sprocket laden according to the engine operating mode of the RSG starter (hereinafter called strand in charge RSG motor) is extended and the no-load strand reported to the motor operating mode of the RSG starter (hereinafter referred to as a strand without RSG load in motor) will be shortened, that is to say stretched. While the RSG-free strand is stretching completely, the crankshaft is already starting to spin. When the strand without load RSG is sufficiently stretched and the internal combustion engine transmits a sufficiently large torque to the starter-generator belt to overcome its inertia (rotational inertia) relatively high, the starter-generator starts moving driven by belt (or its rotor). The belt generator-starter and the other components associated with the drive belt are thus accelerated rather strongly, which can be likened to shock. High forces and loads are applied to the belt starter-generator as well as to the belt and other components connected to the drive belt.

In the case of a combined start-up, the crankshaft is driven by the pinion starter, which is engaged and thus the drive load RSG strand is first lengthened or relaxed. During such a combined start, the starter-belt generator then provides in addition to the torque of the pinion starter, a large torque to accelerate quickly the internal combustion engine. The strand that was previously relaxed will then be tight. High stresses and stresses apply to the belt and other components associated with the drive belt.

The prestressing torque generated during the starting of the internal combustion engine makes it possible to reduce such high loads and high accelerations of the belt starter-generator belt and other components associated with the belt. Shocks and load excursions are avoided in this way. The prestressing torque shortens, that is to say, tends, first of all the starting load strand which, in the case of sprocket starting is the strand without load RSG drive and in the case of combined starting it is the strand in charge RSG drive before the crankshaft starts moving. Then, the pinion starter, if necessary in combination with the starter-generator belt, provide the starting torque needed to start the internal combustion engine.

According to a preferred development of the process, the internal combustion engine is started by the pinion. The starting torque is then supplied only by the pinion starter. In this case, the starter-generator belt advantageously applies a braking torque as preload torque. The braking torque in this context is a torque that acts in the opposite direction to the direction of rotation of the crankshaft, that is to say a torque that opposes that provided by the pinion starter.

The pinion start is for example if, due to different boundary conditions, the starting with the starter-generator belt would not be possible, for example because of a power supply too low by the battery or because of the torque too limited that would provide the starter-generator belt.

The prestressing torque is in particular less than the maximum torque that the starter-belt generator could provide to take into account the present boundary conditions. The prestressing torque shortens, that is to say, prestressing in particular the starting load strand and the belt tensioner toggles towards the starting load strand. As soon as the starting load is sufficiently pre-stressed, the gear start is started. The strand in charge of starting thus remains in particular prestressed until the crankshaft begins to turn. This avoids heavy acceleration and load excursions in the belt drive.

Advantageously, the preload torque will be stopped after the crankshaft has begun to rotate by the starting torque provided by the pinion starter. This prevents the braking preloading torque is exerted on the crankshaft in rotation and slows or unnecessarily interferes with the start of the internal combustion engine. This is done for example by stopping the preload torque controlled by a main control device (for example the engine control unit) by providing a zero torque setpoint to the starter-generator belt.

Preferably, the stopping of the preloading torque can also be performed as a function of the starter-generator belt or its control device. For this, it itself detects the rotational movement of the internal combustion engine or the starter-generator belt and stop immediately after this detection to provide the torque.

According to another advantageous development of the method, a combined start of the internal combustion engine is carried out. In this case, the starting torque is provided in combination with the pinion starter and the belt starter / generator. Advantageously, the starter-generator belt provides the drive torque as a prestressing torque. In this context, the driving torque is the torque that acts in the direction of rotation of the crankshaft or that assists the torque provided by the pinion starter.

This prestressing torque ensuring the drive makes it possible to shorten, that is to say, to preload the strand in charge of starting before the crankshaft starts to rotate. The belt tensioner tilts particularly in the direction of the starting load strand. The crankshaft is still at rest and the starter gear can engage the crankshaft crown. Preferably, as soon as the starter gear is engaged, the starter starts to rotate and provides the torque that will be increased by the engine torque provided by the starter-generator belt. Alternatively, it is also advantageous for the belt starter-generator to first increase the biasing torque when the internal combustion engine begins to rotate. The main control unit (for example, the motor control unit or the starter-generator control unit) controls the increase of the prestressing torque.

The strand in charge of starting is thus sufficiently tight if the starter-generator belt and the starter pinion provide a sufficient starting torque to move the crankshaft. In this case too, high acceleration and load excursions applied to the drive belt are avoided.

A calculation unit according to the invention, for example the vehicle control apparatus, makes it possible to apply the program implementing the method of the invention.

The method according to the invention can also be implemented in the form of a computer program as this results in a very low cost, especially if the control device which executes the program also serves other functions and is available anyway. Suitable data carriers for the program include magnetic, optical or electrical memories such as hard disks, flash memories, EEPROMs, DVDs and others. The program can also be downloaded via a network (Internet, intranet, etc.).

drawings

The present invention will be described hereinafter in more detail with the aid of examples of starting methods of an internal combustion engine shown in the accompanying drawings, in which: FIG. 1 schematically shows an installation composed of a combustion engine; internal combustion, a drive belt, a starter-generator belt and a pinion starter for implementing the method of the invention, Figure 2 shows schematically a preferred embodiment of the method of the invention in the form of a block diagram, FIG. 3 schematically shows the installation of FIG. 1 at the start of the internal combustion engine according to the embodiment of the method of the invention represented in FIG. FIG. 4 schematically shows the diagram of the force applied to the drive belt of a motor vehicle as a function of time, FIG. schematically another preferred embodiment of the method of the invention in the form of a block diagram, and Figure 6 shows schematically the installation of Figure 1 at the start of the internal combustion engine according to the embodiment of the invention. process of Figure 5.

Description of embodiments

FIG. 1 schematically shows an installation 100 according to the invention composed of an internal combustion engine 105 of a motor vehicle, a starter-generator driven by a belt (also called a starter RSG) 130, a pinion starter 110 and a belt connecting these elements.

The internal combustion engine 105 of the vehicle has a crankshaft 151 integral in rotation with a crankshaft drive wheel 150. The crankshaft drive wheel 150 is for example a pulley. Crankshaft 151 is also integral in rotation with a ring gear (this ring is not shown).

The pinion starter 110 comprises, for example, an electric motor and a starter pinion 111. The starter gear 111 can mesh with the ring gear of the crankshaft 151. For example, a starter relay and a lever are provided for this purpose. When the starter pinion 111 is sufficiently engaged in the ring gear, the electric motor rotor of the pinion starter 110 can be rotated and a torque transmitted to the crankshaft 151.

A belt 120, for example a V-belt, connects the crank drive wheel 150 to the RSG starter 130 in the direction of transmission of torque. The belt 120 cooperates in particular by a connection by force and / or shape with the drive wheel 150 of the crankshaft with the drive wheel 131 of the starter RSG 130. The drive wheel 131 is integral in rotation with the rotor The internal combustion engine 105 may be connected by the belt 120 to other components 160 such as a fan, an air conditioning compressor or a refrigerant pump.

The RSG 130 starter can function both as a motor and as a generator. The belt 120 must, under these conditions, allow to transmit a torque in both directions. The belt is thus for example made in the form of a trapezoidal belt. Depending on whether the starter-generator 130 operates as a motor or as a generator, the loaded and the unloaded strand of the belt 120 alternate. In engine mode (in the drive direction of the internal combustion engine) of the generator-starter 130, the belt segment 121 forms the load strand RSG for the engine and the belt segment 122 constitutes the load-free strand RSG of the engine.

There is also provided a belt tensioner 140 for tensioning the belt 120. The belt tensioner 140 is for example in the form of an oscillating tensioner having two pendulum arms 141a, 141b which are in particular connected by a spring mechanism 143. The axes of rotation of the two pendulum arms 141a, 141b are coaxial with the axis of rotation 132 of the driving wheel 131 of the generator-starter 130. Other embodiments of belt tensioner, pendulum or two-armed tensioner of which the axis is not coaxial with that of the generator-starter are also possible solutions. The axis of rotation 132 of the drive wheel 131 thus constitutes at the same time the axis of rotation of the pendulum belt tensioner 120. Each pendulum arm 141a, 141b is connected to a tensioner roller 142a, 142b.

The internal combustion engine 105 is shown in the idle state in FIG. 1. The belt 120 and the swing belt tensioner 140 are thus in the rest position (or intermediate position); they are not deviated.

A control apparatus 170 (engine control unit) notably controls the internal combustion engine 105, the pinion starter 110 and the starter-generator 130. The control unit 170 controls the starting of the internal combustion engine 105 For this, the control apparatus 170 is a preferred embodiment of the method of the invention.

The preferred embodiment of the process of the invention is shown schematically in Figure 2 as a block diagram. FIG. 3 shows the installation 100 at the start of the internal combustion engine 105 according to this preferred embodiment of the method of the invention by a schematic representation.

In this preferred embodiment, the internal combustion engine 105 is started with the pinion start. In step 201 comes a start request, for example by the actuation of the ignition key or the starter button of the vehicle. In step 202, the RSG starter 130 applies a braking torque Mvori as a prestressing torque. This braking torque Mvori acts in the opposite direction to the direction of rotation 152 of the crankshaft 151 of the internal combustion engine 105.

The preloading torque is less than the crankshaft launching torque 151 (torque necessary to put the crankshaft in motion). The preloading torque is for example equal to 2 Nm. The crankshaft 151 is not rotated by this preloading torque, but the preloading torque tends the belt 120 according to step 203. In particular, the strand no load RSG 122 motor will be stretched as strand in charge for starting, ie it will be shortened and the strand in load RSG 121, drive will be relaxed as start vacuum strand it's to say that he will be lying down. The position of the pendulum belt tensioner 140 changes as well as that of the belt 120. The arms of the pendulum tensioner 140 rotate about the axis of rotation 132 by an angle φι towards the start load strand As soon as the strand in charge of starting is sufficiently stretched, in step 204 the starter pinion 111 meshes with the ring gear of the crankshaft. In step 205 the electric motor of the pinion starter 110 rotates the pinion gear 111 and the pinion starter 110 provides the starting torque which is greater than the starting torque of the crankshaft 151. The crankshaft 151 thus begins to rotate and the internal combustion engine 105 is also rotated. As soon as the crankshaft is cut off, the biasing torque MVOri is stopped in step 206. The internal combustion engine 105 continues to turn and starts in step 207.

Tensioning of the starting load strand by the MVOr preloading torque reduces the loads and stresses exerted in the belt drive mode of the plant 100. FIG. 4 schematically shows a diagram showing the force F applied to the belt as a function of time t. The belt 401 describes the force exerted on the belt during the usual pinion starting without creating a prestressing torque. Curve 402 describes the force in the belt during the preferred embodiment described above of the method of the invention. Fo represents the static force in the belt when the internal combustion engine 105 is idling.

According to FIG. 4, a usual start with pinion according to curve 401 generates much greater forces with force excursions than in the starting method of the internal combustion engine according to curve 402. By applying a prestressing torque, it is possible to reduce the forces acting on the belt drive of the plant 100 during the start-up phase. The belt 120, the starter generator 130 and the other components 160 are not accelerated as strongly as in the usual case. Shocks and excursions of load or force are avoided or at least reduced.

Figure 5 shows schematically in the form of a block diagram another preferred development of the method of the invention. FIG. 6 shows the installation 100 at the start of the internal combustion engine 105 according to this preferred embodiment by a schematic representation.

This preferred embodiment applies a combined start of the internal combustion engine 105. A start request appears in step 501. In step 502, the RSG starter 130 generates a motor torque MVOr2 as a preload torque; this torque is lower than the launching torque of the crankshaft 151. This driving torque MVOr2 acts in particular in the direction of rotation 152 of the crankshaft 151 and its value is for example 2 Nm. The belt 120 is thus preloaded in step 503 .

The strand in charge RSG 121, drive, is in this case the strand in charge of starting; the strand without load RSG 122 is in this case the strand without starting load. The preload changes the position of the pendulum tensioner 140 of the belt 120. The arm of the pendulum tensioner 140 pivots about the axis of rotation 132 of the angle q) 2 towards the start load strand. As soon as the starter strand is sufficiently stretched, in step 504, the starter pinion 111 meshes with the ring gear of the crankshaft. As soon as the starter gear 111 is engaged, the torque supplied by the starter RSG 130 can be immediately increased. According to step 511, the starter pinion 111, in gear, is rotated and at the same time the starter torque RSG 130 increases. The RSG 130 starter and the pinion starter 110 generate in combination, the starting torque necessary to launch the crankshaft 151. The crankshaft then begins to rotate and the internal combustion engine 105 will be started in step 512. As soon as the pinion With starter 111 engaged according to step 504, alternatively, the prestressing torque can be further generated by the RSG starter 130. In step 521 the starter gear 111 is rotated in engagement. Thus, the pinion starter 110 and the RSG starter 130 transmit the starting torque to the crankshaft 151. This torque is greater than the launching torque. In step 522 the crankshaft starts moving. Then, in step 523 the RSG starter 130 increases the torque. In combination, the RSG starter 130 and the pinion starter 110 thus apply a greater acceleration torque to start the internal combustion engine 105 and in response, the internal combustion engine 105 starts.

NOMENCLATURE DBS MAIN ELEMENTS 100 Installation 105 Internal combustion engine 110 Pinion starter 120 Belt 121 Belt segment 122 Belt segment

130 RSG 132 Belt Starter / Starter Motor 132 Axle 140 Belt tensioner 141a, 141b Pendulum arms 143 Spring mechanism 150 Crankshaft drive wheel 151 Crankshaft 160 Other component / fan / compressor / pump 170 Engine control unit 201- 207 Stages of the combined starting process 401 Curve representing the force in the belt as a function of time for starting with the pinion starter 402 Curve giving the force in the belt for starting according to the invention

Claims (10)

1 °) Method for starting an internal combustion engine (105) with a starter-generator belt (130) and a starter pinion (110), the internal combustion engine (105) having a crankshaft (151) capable of being connected in the direction of transmission of the torque to the starter-generator belt (130) and the starter gear (110), the starter-generator belt (130) generating a preload torque (MVOri, MVOr2) applied to the crankshaft (151) (steps 202, 502) which acts in the opposite direction to the rotation direction (152) of the crankshaft (151) and which is smaller than the crankshaft launch torque (151), the pinion starter (110) ) alone or the pinion starter (110) and the belt starter-generator (130) applying a starting torque to the crankshaft (151) (steps 205, 521, 522) which is at least equal to the crankshaft launch torque ( 151) and the crankshaft (151) is set in motion (steps 207, 512, 523) by the starting torque. Method according to claim 1, characterized in that for a gear start, the belt starter-generator (130) applies a braking torque (MVori) as a crankshaft pretensioning torque (151) (step 202) and the pinion starter (110) generates the starting torque alone (step 205). 3) Method according to claim 2, characterized in that the preloading torque is no longer applied (step 206) to the crankshaft (151) once the crankshaft (151) is set in motion. 4) Method according to claim 2, characterized in that the starter-generator belt (130) detects the rotational movement of the crankshaft (151) and when this rotational movement is detected, the prestressing torque is no longer applied (step 206) to the crankshaft (151). Method according to Claim 1, characterized in that for a combined start-up, the belt starter-generator (130) applies a motor torque (MVOr2) as a preload torque to the crankshaft (151) (step 502) and the torque The starting motor is generated in combination by the pinion starter (110) and the belt starter-generator (130) (steps 511, 521, 522). Method according to Claim 5, characterized in that the belt starter-generator (130) exerts the prestressing torque (MVOr2) on the crankshaft (151) until the crankshaft (151) begins to rotate ( step 521) and the belt starter-generator (130) increases the torque it provides once the crankshaft (151) begins to rotate (step 522). Method according to claim 5, characterized in that the belt starter-generator (130) exerts the biasing torque (MVor2) to the crankshaft (151) until the pinion starter (110) generates a torque and the belt starter-generator (130) increases the torque it provides as soon as the starter gear (110) has generated a torque (511). 8) The method of claim 1, characterized in that the generated preload torque (MVOri, MVOr2) ensures the tension of the strand in charge of the starter of the belt (120) (steps 203, 503). 9 °) computing unit (170) for applying the method according to any one of claims 1 to 8, with a starter-generator belt (130) and a pinion starter (110), the crankshaft (151) of the engine internal combustion engine (105) being capable of being connected in the direction of transmission of the torque to the starter-generator belt (130) and the starter gear (110), the starter-generator belt (130) generating a torque prestressing device (MVOri, MVOr2) applied to the crankshaft (151) which acts in the direction opposite to the direction of rotation (152) of the crankshaft (151) and which is smaller than the crankshaft starting torque (151), the geared starter ( 110) alone or the pinion starter (110) and the belt starter-generator (130) applying a starting torque to the crankshaft (151) which is at least equal to the crankshaft launch torque (151), and the crankshaft ( 151) is set in motion by the starting torque. Computer program for controlling a computing unit (170) for applying the method according to any one of claims 1 to 8 when executed by the computing unit (170) and readable memory medium by a machine comprising such a computer program.