Soft starter control of a combustion engine of a vehicle

Abstract

The invention relates to a control method implemented in a vehicle comprising an alternator-starter and a starting device, both coupled to a combustion engine respectively via a belt and a coupling device when the coupling device has been placed in a coupled state. This method comprises a step (10-40) wherein the coupling device is placed in its coupled state, then a first torque is supplied by the alternator-starter to the belt in order to pre-tension the belt, and a second torque is supplied by the starting device to the coupling device in order to overcome coupling play. The combustion engine is then started up by simultaneously supplying third and fourth torques, which are respectively greater than the first and second torques, from the alternator-starter and starting device.

Description

DESCRIPTION TITLE: CONTROL OF THE SMOOTH START OF A VEHICLE'S HEAT ENGINE The present invention claims priority from French application No. 2213148 filed on 12.12.2022, the content of which (text, drawings and claims) is incorporated herein by reference. Technical field of the invention

[0001] The invention relates to vehicles comprising a powertrain (or GMP) comprising at least one thermal motor (or engine), and more precisely to the control of the starting of such a thermal motor (or engine). State of the art

[0002] Some vehicles, possibly of the automobile type, comprise a powertrain (or GMP) comprising at least one thermal motor (or engine) that can be started by an alternator-starter and a starting device (such as, for example, an electric machine possibly installed in a gearbox). In this case, the alternator-starter is coupled to the thermal engine via a belt (generally coupled to the crankshaft of the latter), and the starting device can be coupled to the thermal engine via a coupling device (generally a clutch). This type of vehicle is described in particular in patent document FR-B1 3 101 679.

[0003] In order to reduce the vibrations generated by starting the thermal engine, and resulting from alternating accelerations during the first internal combustions, but also the premature wear of the belt, the aforementioned patent document proposes to implement a method comprising, after placing the coupling device in its coupled (or closed) state:

[0004] - a first step in which a first torque is supplied to the belt by means of the alternator-starter, and after a brief instant a second torque is supplied to the coupling device with the starting device to cause the thermal engine to rev up, and

[0005] - a second stage in which the first torque is stopped when the engine speed reaches a chosen threshold.

[0006] It will be understood that such a method has the aim, during a starting phase by the starting device, of providing the belt with a first torque with the alternator-starter in order to limit the slippage of this belt and to facilitate the starting of the thermal engine. In other words, the first torque provided by the alternator-starter is not intended to start the thermal engine, but to limit the impact of the alternating accelerations during the first combustions on the dynamics of the drive.

[0007] Unfortunately, this method does not sufficiently reduce the vibrations and tremors caused by the first combustions, which is a nuisance for the vehicle's passengers. In addition, this method generates other mechanical noises (in addition to those caused by the first combustions) due to the difficulty of reducing the "plays" of the starting device at the very beginning of the combustion engine's start.

[0008] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0009] For this purpose, it proposes in particular a control method intended to be implemented in a vehicle comprising an alternator-starter and a starting device coupled to an engine. thermal via respectively a belt and a coupling device when the latter has been placed in a coupled state.

[0010] This control method is characterized by the fact that it comprises a step in which the coupling device is placed in its coupled state, then a first torque is supplied with the alternator-starter to the belt in order to obtain a pre-tension of the latter and a second torque is supplied with the starting device to the coupling device in order to overcome coupling clearances, then the thermal engine is started by simultaneously supplying third and fourth torques respectively greater than the first and second torques with the alternator-starter and starting device.

[0011] This not only avoids the vibrations and tremors caused by the first combustions, but also the generation of mechanical noise, which allows a smooth start with minimal inconvenience for the vehicle's passengers.

[0012] The control method according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0013] - in its step, when the second torque is provided with the starting device, it is also possible to provide the belt, with the alternator-starter, with a fifth torque greater than the first torque and less than the third torque;

[0014] - in its step, the first couple can be chosen according to a current temperature of a chosen fluid circulating in the heat engine;

[0015] - in its step, the third couple can be chosen as a function of a current temperature of a fluid circulating in the heat engine and / or a chosen speed of the heat engine and / or a duration during which the heat engine has been stopped;

[0016] - in its step, the fourth couple can be chosen according to a current temperature of a fluid circulating in the heat engine and / or a chosen speed of said heat engine and / or a duration during which the heat engine was stopped;

[0017] - in its step, the fluid can be chosen from an oil and a heat transfer fluid from a cooling circuit associated with the heat engine;

[0018] - in its step, the third and fourth torques can be supplied simultaneously as long as a current speed of the thermal engine is lower than a chosen idle speed of the thermal engine.

[0019] The invention also provides a computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing a control method of the type presented above, in a vehicle comprising an alternator-starter and a starting device coupled to a heat engine via respectively a belt and a coupling device when the latter has been placed in a coupled state, to start the heat engine.

[0020] The invention also proposes a control device intended to equip a vehicle comprising an alternator-starter and a starting device coupled to a heat engine via respectively a belt and a coupling device when the latter has been placed in a coupled state.

[0021] This control device is characterized by the fact that it comprises at least one processor and at least one memory arranged to carry out the operations consisting of triggering a placement of the coupling device in its coupled state, then triggering a supply with the alternator-starter of a first torque to the belt in order to obtain a pre-tension of the latter and a supply with the starter device of a second torque to the coupling device in order to overcome coupling clearances, then causing a start of the thermal engine by triggering a simultaneous supply of third and fourth torques respectively. higher than the first and second pairs with the alternator-starter and starting device.

[0022] The invention also proposes a vehicle, possibly of the automobile type, and comprising, on the one hand, an alternator-starter and a starting device coupled to a thermal engine via respectively a belt and a coupling device when the latter has been placed in a coupled state, and, on the other hand, a control device of the type presented above. Brief description of the figures

[0023] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0024] [Fig. 1] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a control device according to the invention and a GMP transmission chain, with a thermal motor associated with an alternator-starter and a starting device, and associated with a supervision computer,

[0025] [Fig. 2] schematically and functionally illustrates an exemplary embodiment of a supervision computer comprising an exemplary embodiment of a control device according to the invention,

[0026] [Fig. 3] schematically illustrates an example of an algorithm implementing a control method according to the invention, and

[0027] [Fig. 4] schematically illustrates within a first diagram an example of temporal evolution of the state of the coupling device (eoci) in a starting phase of the thermal motor, within a second diagram an example of temporal evolution of the torque (CAD) provided by the alternator-starter in this starting phase, within a third diagram an example of temporal evolution of the torque (CDD) provided by the starting device in this starting phase, and within a fourth diagram an example of the temporal evolution of the thermal motor engine speed (rm) in this starting phase. Detailed description of the invention

[0028] The invention aims in particular to propose a control method, and an associated DC2 control device, intended to enable control of the smooth starts of an MT thermal motor of a vehicle V.

[0029] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car, as illustrated in figure 1. But the invention is not limited to this type of vehicle. It relates in fact to any type of vehicle comprising a GMP transmission chain with a thermal prime mover associated with an alternator-starter and a starting device. Thus, it relates to land vehicles (utility vehicles, camper vans, minibuses, coaches, trucks, motorcycles, road machinery, construction machinery, agricultural machinery, leisure machinery (snowmobile, kart), tracked vehicles, trains and trams, for example), aircraft and boats.

[0030] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a transmission chain with a hybrid type powertrain (or GMP) (thermal and electric, and therefore whose drive is provided mainly by a thermal motor (or a thermal engine) MT and secondarily by the starting device DD). But the GMP could be purely thermal.

[0031] Figure 1 schematically shows a vehicle V comprising a hybrid GMP transmission chain (and therefore in particular with a thermal motor MT and an electric starting device DD which also optionally has an electric motor function), a supervision computer CS, a supply battery BA, an alternator-starter AD associated with a DC belt, a DD starting device, and a DC2 control device according to the invention.

[0032] The transmission chain has a GMP which is, here, hybrid and therefore which includes, in particular, a thermal motor (or engine) MT and at least the starting device DD, this starting device DD having for example in addition an electric motor function. It will be noted that in the example illustrated, this electric motor function is integrated into the starting device DD which we will return to later.

[0033] Furthermore, the transmission chain also includes, here, an AM motor shaft, a DC1 coupling device, a BV gearbox, and an AT transmission shaft.

[0034] The operation of the transmission chain (and therefore of the GMP) is supervised by a CS supervision computer.

[0035] The MT thermal engine comprises a crankshaft (not shown) which is fixedly secured to the AM engine shaft in order to drive the latter (AM) in rotation. This MT thermal engine is intended to supply torque, on command from the CS supervision computer, for at least one T1 set of driving wheels, via the DC1 coupling device and the BV gearbox.

[0036] For example, the train T1 can be located in the front part PW of the vehicle V. It is preferably, and as illustrated, coupled to the transmission shaft AT via a differential (here front) DV. But in a variant this train T1 could be the one referenced T2 which is located in the rear part PRV of the vehicle V.

[0037] For example, the DC1 coupling device could be a clutch. But it could also be a torque converter or a dog clutch.

[0038] By way of non-limiting example, the BV gearbox may comprise a MBV gear change mechanism of the so-called “dual clutch (or DCT)” type. However, the invention is not limited to this type of gearbox.

[0039] The MT engine crankshaft is also coupled to a CC belt, which is itself coupled to an AD alternator-starter which is supplied with electrical energy by a BA supply battery (and which can also recharge the latter (BA)). Thus, the AD alternator-starter can supply CAD torque to the CC belt, which can supply this CAD torque to the crankshaft.

[0040] It should be noted that this BA power supply battery can, for example, be of the 48 V type. But this is not an obligation. Indeed, it could alternatively be of the 12 V, 24 V, or 400 V type for example.

[0041] The starting device DD can be coupled to the thermal engine MT via the coupling device DC1 when the latter (DC1) has been placed in a coupled (or fully closed) state. It will therefore be understood that when the coupling device DC1 has been placed in an uncoupled (or fully open) state, the starting device DD is decoupled from the thermal engine MT. It will be noted that the coupling device DC1 can also be, possibly, placed in a slip state, namely a state in which the coupling device DC1 is not fully closed (or 100% engaged), but however more closed (in percentage) than when it is in its licking state (or point) from which it allows the crankshaft to start transmitting torque to the primary shaft AP of the gearbox BV so that the vehicle V can start moving.

[0042] As indicated previously, it is considered in the following, by way of illustrative example, that the starting device DD is an electric motor, for example supplied with electrical energy by the supply battery BA. Furthermore, it is also considered in the following, by way of illustrative example, that the starting device DD is an (electric) motor of the GMP, and therefore can provide torque to move the vehicle V. But in an alternative embodiment the starting device DD could not be an electric motor. Thus, it could, for example, be a starter, the important thing being that it can be coupled to the MT thermal engine via the DC1 coupling device.

[0043] It should be noted that in the example illustrated without limitation in Figure 1, the DD starting device is part of the BV gearbox. But this is not an obligation.

[0044] As mentioned above, the invention notably proposes a control method intended to enable the control of smooth starts of the MT thermal engine.

[0045] This (control) method can be implemented at least partially by the control device DC2 (illustrated at least partially in Figures 1 and 2) which comprises for this purpose at least one processor PR1, for example a digital signal processor (or DSP ("Digital Signal Processor")), and at least one memory MD. This control device DC2 can therefore be implemented in the form of a combination of electrical or electronic circuits or components (or "hardware") and software modules (or "software"). For example, it can be a microcontroller.

[0046] The MD memory is RAM in order to store instructions for the implementation by the processor PR1 of at least part of the control method. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0047] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC2 is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC2 could include its own dedicated computer, which is then coupled to the supervision computer CS, or could be part of another computer on board the vehicle V and providing at least one other function, for example.

[0048] As illustrated non-limitingly in Figure 3, the (control) method according to the invention comprises a step 10-40 which is implemented each time the thermal engine MT must be started.

[0049] Step 10-40 of the method comprises a sub-step 10 in which the control device DC2 begins by placing the (the control device DC2 begins by triggering the placement of the) coupling device DC1 in its coupled state. It will be noted, as illustrated non-limitingly in the first diagram (the topmost (eoci = f(t))) of Figure 4, that this placement from the uncoupled state to the coupled state can possibly be done via an intermediate placement in a sliding state.

[0050] For example, this sub-step 10 can begin once the driver of the vehicle V requests the starting of the latter (V) by a dedicated action with a starter key or by pressing a dedicated control member, for example, or in the event of detection of the opening of the door dedicated to the driver.

[0051] Step 10-40 of the method also includes a sub-step 20 in which a first torque c1 is supplied (the control device DC2 triggers the supply) with the alternator-starter AD to the belt CC in order to obtain a pre-tension of the latter (CC).

[0052] It will be understood that this sub-step 20 can only begin on condition that the alternator-starter AD is ready to supply torque CAD.

[0053] It is important to note that the value of the first torque c1 does not allow, whatever the current temperature of the MT thermal engine, to trigger what those skilled in the art call a "tearing off" of the MT thermal engine, that is to say an increase in the rm speed of the latter (MT).

[0054] For example, the first torque c1 can be between 1 Nm and 10 Nm. When this first torque c1 is constant, it can, as an illustrative example, be equal to 5 Nm.

[0055] But this first couple c1 can be variable. Thus, it can, for example, be chosen according to the current temperature of a chosen fluid circulating in the MT heat engine. Such a fluid can, for example, be oil or a heat transfer fluid from a cooling circuit which is associated with the MT heat engine.

[0056] In this sub-step 20, or in a sub-step 30 of step 10-40 (as illustrated in Figure 3), a second torque c2 is also supplied (the control device DC2 also triggers the supply) with the starting device DD to the coupling device DC1 in order to overcome coupling clearances of the starting device DD to the crankshaft.

[0057] When the method comprises a sub-step 30, the end of sub-step 20 occurs when the alternator-starter AD actually supplies the first torque c1 to the belt CC. Furthermore, this sub-step 30 can only begin on condition that the starter device DD has been activated, and therefore is capable of being torque-controlled and of supplying torque CDD to the coupling device DC1.

[0058] When the method does not include sub-step 30, the first c1 and second c2 pairs are provided substantially at the same time in order to reduce the start-up time perceived by the passengers of the vehicle V.

[0059] It is important to note that the value of the second torque c2 does not allow, whatever the current temperature of the MT thermal engine, to trigger a tearing of the MT thermal engine. The purpose of c2 is in fact to overcome the coupling clearances of the starting device DD to the crankshaft before the real start (increase in the speed rm of the MT thermal engine) begins.

[0060] Preferably, the value of the second torque c2 is slightly greater than the value of the first torque c1. For example, the second torque c2 may be between 3 Nm and 15 Nm. When this second torque c2 is constant, it can, as an illustrative example, be equal to 8 Nm.

[0061] But this second couple c2 can be variable. Thus, it can, for example, be chosen according to the current temperature of a chosen fluid circulating in the MT heat engine. Such a fluid can, for example, be oil or a heat transfer fluid from a cooling circuit which is associated with the MT heat engine.

[0062] Step 10-40 of the method also comprises a sub-step 40 in which the (control device DC2 triggers the starting of the) thermal engine MT is started by simultaneously providing a third torque c3 greater than the first torque c1 with the alternator-starter AD, and a fourth torque c4 greater than the second torque c2 with the starting device DD.

[0063] The word "simultaneously" has a broad definition here. It means in fact that during at least part of the sub-step 40 the alternator-starter AD and starting device DD simultaneously supply respectively third c3 and fourth c4 torques, as appears in the examples of the second and third diagrams of figure 4). It is important to note that the value of the third torque c3, like the value of the fourth torque c4, is capable, whatever the current temperature of the thermal engine MT, of triggering a disconnection of the thermal engine MT and therefore of driving the thermal engine MT in rotation until it is made autonomous in rotation by its own combustions.

[0064] Thanks to the pre-tensioning of the CC belt and the passage of the clearances, not only are the vibrations and tremors caused by the first combustions now avoided, but also the generation of mechanical noise and premature wear of the CC belt. In addition, the joint use of the alternator-starter AD and the starting device DD to together cause the effective start in sub-step 40 makes it possible to facilitate the start and reduce its duration. This provides a smooth start with minimal inconvenience to the passengers of vehicle V.

[0065] It will be noted that in sub-step 30 of step 10-40, when the second torque c2 is supplied with the starting device DD, it is also possible to supply (the control device DC2 can also trigger the supply) to the belt CC, with the alternator-starter AD, a (of a) fifth torque c5 which is greater than the first torque c1 and less than the third torque c3.

[0066] It is important to note that the value of the fifth torque c5 does not allow, whatever the current temperature of the MT thermal engine, to trigger a tearing of the MT thermal engine. The purpose of c5 is in fact to facilitate the driving of the crankshaft at the very beginning of the increase in speed rm of the MT thermal engine.

[0067] In this case, the end of sub-step 20 (in the absence of sub-step 30), or the end of sub-step 30, occurs when the alternator-starter AD actually supplies the fifth torque c5 to the belt CC.

[0068] For example, the fifth torque c5 can be between 20 Nm and 40 Nm. When this fifth torque c5 is constant, it can, as an illustrative example, be equal to 30 Nm.

[0069] But this fifth couple c5 can be variable. Thus, it can, for example, be chosen according to the current temperature of a chosen fluid circulating in the MT heat engine. Such a fluid can, for example, be oil or a heat transfer fluid from a cooling circuit which is associated with the MT heat engine.

[0070] It will also be noted that in sub-step 40 of step 10-40 the third couple c3 can be chosen as a function of the current temperature of a fluid circulating in the MT heat engine and / or a chosen speed of the MT heat engine and / or the duration during which the MT heat engine has been stopped.

[0071] When the third couple c3 is chosen at least as a function of the current temperature of a fluid, the latter can, for example, be oil or a heat transfer fluid from a cooling circuit which is associated with the MT heat engine.

[0072] It will also be noted that in sub-step 40 of step 10-40 the fourth couple c4 can be chosen as a function of the current temperature of a fluid circulating in the MT heat engine and / or a chosen speed of the MT heat engine and / or the duration during which the MT heat engine has been stopped.

[0073] When the fourth couple c4 is chosen at least as a function of the current temperature of a fluid, the latter can, for example, be oil or a heat transfer fluid of a cooling circuit which is associated with the MT heat engine.

[0074] It will also be noted that in sub-step 40 of step 10-40 the third c3 and fourth c4 torques can be supplied simultaneously (the control device DC2 can also trigger the simultaneous supply of) as long as the current speed rm of the thermal engine MT is lower than a chosen idle speed of the thermal engine MT. Consequently, once this chosen idle speed is reached, it is possible either to completely stop supplying torque to the belt CC and to the coupling device DC1, or to start by significantly reducing the values ​​of the torques supplied to the belt CC and to the coupling device DC1 before completely stopping these supplies, as illustrated non-limitingly in the second and third diagrams of figure 4.

[0075] Figure 4 schematically illustrates an example of implementation of the method according to the invention for starting the MT heat engine. The first diagram illustrates an example of the temporal evolution of the state eoci of the coupling device DC1 in a starting phase of the MT heat engine. The second diagram illustrates an example of the temporal evolution of the torque CAD which is provided by the alternator-starter AD in this starting phase. The third diagram illustrates an example of the temporal evolution of the torque CDD which is provided by the starting device DD in this starting phase. The fourth diagram illustrates an example of the temporal evolution of the rm speed of the MT thermal engine in this starting phase.

[0076] At a time t1, the coupling device DC1 is triggered to be placed in its coupled state, here via a sliding state. At a time t2, while the coupling device DC1 is not yet placed in its coupled state, the supply with the alternator-starter AD of a first torque c1 to the belt CC is triggered in order to obtain the pre-tension of the latter (CC).

[0077] At a time t3 the coupling device DC1 is placed in its coupled state and the alternator-starter AD effectively supplies the first torque c1, and therefore the joint supply of the fifth torque c5 to the belt CC with the alternator-starter AD and the second torque c2 to the coupling device DC1 with the starting device DD is triggered in order to overcome the coupling clearances of the starting device DD to the crankshaft.

[0078] When the second c2 and fifth c5 couples are actually supplied at time t4, the joint supply of the third couple c3 with the alternator-starter AD and the fourth couple c4 with the starting device DD is triggered, to start the thermal engine MT.

[0079] At time t5, the current speed rm of the MT thermal engine becomes higher than the chosen idle speed (see the fourth diagram (lowest)), and therefore the values ​​of the torques supplied to the CC belt and to the DC1 coupling device are significantly reduced. Then, at time t6, the supply of torques to the CC belt and to the DC1 coupling device is substantially and completely stopped at the same time, because it is considered that the MT thermal engine has actually started.

[0080] The torque CAD which is supplied by the alternator-starter AD can therefore alternately take the three different torque values ​​according to the invention: the first torque C1, the third torque C3, or the fifth torque C5. The torque CDD which is supplied by the starting device DD can therefore take alternatively the two different torque values: the second torque C2, or the fourth torque C4.

[0081] It will also be noted, as illustrated non-limitingly in Figure 2, that the supervision computer CS (or the computer of the control device DC2) can also comprise a mass memory MM1, in particular for storing the measurements of the CAD and CDD torques which are actually supplied, as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision computer CS (or the computer of the control device DC2) can also comprise an input interface IE for receiving at least the measurements of the CAD and CDD torques actually supplied and the requests to start the thermal engine MT to use them in calculations or processing, possibly after having formatted and / or demodulated and / or amplified it, in a manner known per se, by means of a digital signal processor PR2.In addition, this supervision calculator CS (or the calculator of the control device DC2) can also comprise an output interface IS, in particular for delivering a message (or order) for placing the coupling device DC1 in its coupled state, a message (or order) for supplying the first pair c1, a message (or order) for supplying the second pair c2, a message (or order) for supplying the third pair c3, a message (or order) for supplying the fourth pair c4, a possible message (or order) for supplying the fifth pair c5, and messages or orders for stopping supply of the pairs CAD and CDD.

[0082] It will also be noted that the invention also proposes a computer program product (or computer program) comprising a set of instructions which, when executed by processing means of the electronic circuit (or hardware) type, such as for example the processor PR1, is capable of implementing the method control described above to smoothly start the thermal engine MT of vehicle V.

Claims

CLAIMS

1. Control method for a vehicle (V) comprising an alternator-starter (AD) and a starting device (DD) coupled to a heat engine (MT) via a belt (CC) and a coupling device (DC1) respectively when the latter (DC1) has been placed in a coupled state, characterized in that it comprises a step (10-40) in which said coupling device (DC1) is placed in its coupled state, then a first torque is supplied with said alternator-starter (AD) to said belt (CC) in order to obtain a pre-tension of the latter (CC) and a second torque is supplied with said starting device (DD) to said coupling device (DC1) in order to overcome coupling clearances, then said heat engine (MT) is started by simultaneously supplying third and fourth torques respectively greater than said first and second torques with said alternator-starter (AD) and starting device (DD).

2. Method according to claim 1, characterized in that in said step (10-40), when said second torque is provided with said starting device (DD), said belt (CC) is also provided, with said alternator-starter (AD), with a fifth torque greater than said first torque and less than said third torque.

3. Method according to claim 1 or 2, characterized in that in said step (10-40) said first torque is chosen as a function of a current temperature of a chosen fluid circulating in said heat engine (MT).

4. Method according to one of claims 1 to 3, characterized in that in said step (10-40) said third torque is chosen as a function of a chosen current temperature of a fluid circulating in said heat engine (MT) and / or a chosen speed of the heat engine (MT) and / or a duration during which said heat engine (MT) has been stopped.

5. Method according to one of claims 1 to 4, characterized in that in said step (10-40) said fourth torque is chosen as a function of a current temperature of a fluid circulating in said heat engine (MT) and / or of a chosen speed of said heat engine (MT) and / or of a period during which said thermal engine (MT) was stopped.

6. Method according to one of claims 3 to 5, characterized in that in said step (10-40) said fluid is chosen from an oil and a heat transfer fluid of a cooling circuit associated with said heat engine (MT).

7. Method according to one of claims 1 to 6, characterized in that in said step (10-40) said third and fourth torques are simultaneously supplied as long as a current speed of said heat engine (MT) is lower than a chosen idle speed of said heat engine (MT).

8. Computer program product comprising a set of instructions which, when executed by processing means, is capable of implementing the control method according to one of claims 1 to 7, in a vehicle (V) comprising an alternator-starter (AD) and a starting device (DD) coupled to a heat engine (MT) via respectively a belt (CC) and a coupling device (DC1) when the latter (DC1) has been placed in a coupled state, to start said heat engine (MT).

9. Control device (DC2) for a vehicle (V) comprising an alternator-starter (AD) and a starting device (DD) coupled to a heat engine (MT) via respectively a belt (CC) and a coupling device (DC1) when the latter (DC1) has been placed in a coupled state, characterized in that it comprises at least one processor (PR1) and at least one memory (MD) arranged to carry out the operations consisting of triggering a placement of said coupling device (DC1) in its coupled state, then triggering a supply with said alternator-starter (AD) of a first torque to said belt (CC) in order to obtain a pre-tension of the latter (CC) and a supply with said starting device (DD) of a second torque to said coupling device (DC1) in order to overcome coupling clearances,then to cause a start of said thermal engine (MT) by triggering a simultaneous supply of third and fourth torques respectively greater than said first and second torques with said alternator-starter (AD) and starting device (DD).,

10. Vehicle (V) comprising an alternator-starter (AD) and a starting device (DD) coupled to a heat engine (MT) via respectively a belt (CC) and a coupling device (DC1) when the latter (DC1) has been placed in a coupled state, characterized in that it further comprises a control device (DC2) according to claim 9.

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