FR2982328A1 - Starter system for thermal engine of drive train of terrestrial vehicle i.e. car, has starter mechanically connected to thermal engine, and transmission output control connected with box and clutch by fluidic connection - Google Patents

Abstract

The system (10) has a pressure medium starter (20) using fluidic energy provided by fluid sources (22, 24), where the starter is mechanically connected to a thermal engine (14). A fluid distribution unit (35) is provided with fluid supply inlets (28, 36A) that are connected to a fluid outlet (42) by fluidic connection. The fluid outlet is connected to the starter. A transmission output control (44) is connected with a box (16) and a clutch (18) by fluidic connection. The starter comprises an engine (20A) having a primary port (20P) and a secondary port (20S). An independent claim is also included for a car.

Description

The present invention relates to a starting system for a heat engine associated with a gearbox and a clutch. The patent application US2011 / 0118963 describes such a starting system, of the hydraulic type, for a vehicle with stop function and automatic restart of the engine. This function is called "start / stop" in this patent but is commonly called "stop and start" or "stop and go" 10 by some car manufacturers. Such a function stops the engine when the vehicle is completely stopped, for example at a red traffic light or in a traffic jam, and automatically restarts it for example when the driver acts on the clutch, on the accelerator pedal , engages a gear ratio according to the type of vehicle, for example manual or automatic gearbox. The goal is to save fuel when it is not necessary for the engine to run. In US2011 / 0118963, the starter system is relatively complex. The present invention is intended to overcome the disadvantages of the prior art and improve existing systems. The present invention has applications other than automotive, but in this context, when the starting function becomes more solicited in the case of vehicles with "start / stop" function, it becomes necessary to find a starter solution to respond. to certain criteria of power, response time, compactness and robustness. Hydraulic starting systems advantageously meet these criteria. For this purpose, the invention relates to a starting system for a heat engine associated with a gearbox and a clutch, at least one of this gearbox and this clutch being automated by actuators using the energy of a pressurized fluid supplied by a source of said fluid, comprising a pressurized fluid starter adapted to use the fluidic energy supplied by said pressurized fluid source and adapted to be mechanically connected to the heat engine to be able to start it, and a fluid distribution unit having a fluid supply inlet adapted to be fluidly connected to said source, having a fluidic starter output fluidly connected to the starter and a transmission pilot output intended to be connected by fluidic connection at least to one of the box and the clutch. In various embodiments of the starter system according to the invention, one or more of the following may also be used: - the pressurized-fluid starter comprises a motor having a port main and a secondary port which are fluidically connected to the fluid distribution unit so that the main port can receive pressurized fluid from the starting fluid outlet for the starter to start the engine. ; the engine of the pressurized-fluid starter 25 is a reversible engine capable, on the one hand, of consuming energy of the pressurized fluid supplied by the source of fluid under pressure, to start the engine, and on the other hand to produce pressurized fluid energy for supplying an accumulator belonging to the source of fluid under pressure; the engine of the pressurized fluid starter is a hydraulic motor; the fluid distribution unit comprises a selection valve which can be in a state of rest placing the fluid supply inlet in communication with the transmission control output, for the supply of one of the box and the clutch, and isolating the starter from said supply input so that the starter is at a standstill, or can be at a start state of the heat engine in which the fluid supply inlet communicates with the fluidic starter output for starting the heat engine; the selection valve can be in a state of energy recovery, on the one hand communicating the secondary port of the starter motor with the fluid supply inlet of the fluid distribution unit and on the other hand part of the main port of said engine with a return port of said unit; the fluid distribution unit comprises a bypass valve which is interposed between on the one hand the selection valve and on the other hand the transmission control output and the return port of said unit, which can be at a quiescent state communicating, via the selection valve to its quiescent state, the fluid supply inlet of the fluid distribution unit with the transmission control output and which may be in a second state communicating the starter motor with the return port, via the selection valve which is at its start state or at its energy recovery state by further placing the starter motor in communication with the power input in fluid. Furthermore, the subject of the invention is also a power train assembly comprising a heat engine associated with a gearbox and a clutch, at least one of this gearbox and this clutch being automated by pressurized fluid actuators. being associated with a transmission control module and a starting system according to the invention, the transmission control output of which is connected by fluid connection to the transmission control module and whose starter is mechanically connected to the engine.

In one embodiment of this assembly, the starter is mechanically connected to the engine having a pinion coupled to the flywheel of the engine.

In another embodiment of this assembly, the starter is mechanically connected to the heat engine by having a pinion coupled to a transmission reduction ratio pinion gear, this reduction ratio pinion being engaged with a primary shaft of the gearbox. the gearbox. Furthermore, the subject of the invention is also a motor vehicle comprising a passenger compartment receiving, on the one hand, an accelerator for controlling the load on the engine and, on the other hand, an interface for putting the engine in the on mode or in the stop mode, a source of pressurized fluid, a control unit of the heat engine and a motor-driven assembly that is in accordance with the invention. In this vehicle, in running mode of the engine, the control unit of the engine stops the engine as soon as the vehicle is stopped and restart the engine as soon as a command occurs on the throttle, on the clutch or on the gearbox.

Other objects, features and advantages of the invention will become apparent from the following description of several embodiments, given by way of non-limiting examples, with reference to the accompanying drawings.

In the drawings: FIG. 1 is a schematic diagram of a hydraulic system of a starter system according to the invention as it is implanted in engagement with a heat engine associated with a gearbox and a clutch, in operating state at rest ; FIG. 2 is a schematic diagram of the hydraulic circuit of FIG. 1, in the starting operating state of the engine; FIG. 3 is a hydraulic circuit diagram of FIG. 1, in energy recovery operating state; FIG. 4 is a block diagram of a variant of the hydraulic system of a starter system according to the invention, without a function of energy recovery; - Figure 5 is a block diagram of the implementation of the starter system according to the invention as implanted to start a heat engine linked to a gearbox single clutch; FIG. 6 is a block diagram of the implementation of the starter system according to the invention as set up to start a heat engine linked to a double clutch gearbox. In the different figures, the same references denote identical or similar elements. Referring to the figures, the reference 10 designates a starting system according to the invention, associated with a heat engine 14 attached to a gearbox 16 and a clutch 18. A flywheel 14A is integral with the output shaft of the engine. thermal engine 14, the side of the clutch 18. At least one of this box 16 or clutch 18 is automated by actuators using the energy of a fluid under pressure. In the embodiments which will be described, the gearbox 16 and the clutch 18 are hydraulically controlled by a hydraulic transmission control module 19. A pressurized fluid circuit for supplying hydraulic power to the gearbox 16 and the clutch 18 also serves to feed a pressurized fluid starter, here constituted by a hydraulic starter 20. The starter 20 comprises a hydraulic motor 20A and an output shaft 20B which, in the embodiment shown in Figures 1 to 3, has a pinion 20C meshing with the flywheel 14A.

An electric pump unit 22 supplies the pressurized oil to the hydraulic circuit comprising an accumulator 24 of pressurized fluid. A check valve 26 is interposed between the electropump 22 and the accumulator 24 which constitute a source of fluid under pressure. The electro-pump unit 22 is powered by pumping the hydraulic fluid contained in a return tank 25 via a reserve line 22R. The return tank 25 is directly connected by a steering return pipe 19R to the hydraulic transmission control module 19. A feed line 28 leaves between the accumulator 24 and the check valve 26, to supply a starting module of the heat engine 30. The starting module of the heat engine 30 comprises the hydraulic starter 20, a control module 34 and a fluid distribution unit 35 to at least one selection valve 36. Under the control of the start control module 34, the fluid distribution unit 35 on the one hand starts the engine 14 by supplying pressurized fluid to the starter 20 and secondly the pressurized supply of the gearbox 16 and the clutch 18 via the hydraulic transmission control module 19. In the embodiment shown in FIGS. 1 to 3, the fluid distribution unit 35 also allows the operation of the starter 20 in energy recovery mode so that it is also a generator of pressurized fluid supplying the accumulator. 24. For this energy recovery function, the starting module of the heat engine 30 comprises, in its fluid distribution unit 35, a bypass valve 38 interposed between the selection valve 36 and the hydraulic module 19 of the transmission control. In the embodiment shown in FIGS. 1 to 3, the selection valve 36 is constituted by a distributor with three positions and four orifices, actuated by electromagnets 39A and by return spring 39B in the central position of rest. The bypass valve 38 is constituted by a distributor with two positions and three ports, actuated by an electromagnet 39A and by a return spring 39B in the rest position. The control in position of the selection valve 36 and the bypass valve 38 is performed by the start control module 34 via the electrical connections 34A. The selector valve 36 has a supply inlet 36A connected to the supply line 28 and a loopback inlet 36B connected by a first start line 41 to a secondary port 20S of the hydraulic motor 20A of the starter 20. The valve selecting means 36 has a start output 36D connected by a second start line 42 to a main port 20P of said motor 20A. The selector valve 36 has a control output 36P connected by a control line 44 to the bypass input 38E of the bypass valve 38. The selection valve 36 has three stages, namely a central stage of direct communication. 37D, a cross communication side stage 37C and a diverting side stage 37T. The direct communication central stage 37D is able to connect on the one hand the supply input 36A with the control output 36P and on the other hand the loopback input 36B with the startup output 36D. The cross communication side stage 37C is able to connect on the one hand the loopback input 36B with the control output 36P and on the other hand the supply input 36A with the startup output 36D. The lateral diversion stage 37T is able to connect on the one hand the supply input 36A with the loopback input 36B and on the other hand the startup output 36D with the control output 36P. The bypass valve 38 has two stages, namely a deflected communication stage 38V and a right communication stage 38T. The diverted communication stage 38V is able to connect the bypass input 38E with the pressure output 38P. The right communication stage 38T is capable of connecting the bypass input 38E with the return output 38R. The pressure output 38P is connected with a fluid output line called the transmission control output line 46 because it is dedicated to the supply of the transmission control hydraulic module 19. The feedback output 38R is connected with a return return line 30R which constitutes a return port for the fluid distribution unit 35. The starter module 30 also includes a pressure limiter 52 allowing the flow of fluid between the first start line 41 and the second starting line 42. The operation of the starter system 10 is already apparent in part from the foregoing description and will now be detailed. This system 10 may alternatively be in an idle state of operation, a start-up operating state of the heat engine, and an energy recovery operating state. The start control module 34 controls the electromagnets 39A of the selector valve 36 and the bypass valve 38. These valves return to rest by their return springs 39B.

In its rest state as shown in Figure 1, it is the central stage 37D of the selection valve 36 which is implemented for the circulation of fluid. In addition, it is the deflected communication stage 38V of the bypass valve 38 which is used for the circulation of fluid. Thus, when the starter module 30 is at rest, the supply line 28 is in communication with the control duct 44 which is in communication with the transmission control output duct 46 supplying the hydraulic transmission control module 19 The supply line 28 is the input of both the starter module 30 and its fluid distribution unit 35.

The source of hydraulic pressure constituted by the accumulator 24 and the electric pump unit 22 thus feeds here the hydraulic transmission control module 19 which allows the gearbox 16 and the clutch 18 to operate normally, being supplied with power. hydraulic pressure and being controlled by said module 19. The electric pump unit 22 and the accumulator 24 provide the hydraulic pressure at the input of the starter module 30 which transmits this pressure to the control module 19 to the gearbox and the clutch then the pilot return pipe 19R brings back fluid to the return tank 25 in which the electric pump unit 22 sucks. In its starting operating state of the heat engine, as represented in FIG. 2, the starting system 10 on the one hand, the lateral cross communication stage 37C of the selection valve 36 and, on the other hand, the right communication stage 38T of the In this way, the supply line 28 is in communication with the second start line 42 so that the hydraulic pressure source, namely the accumulator 24 and the electric pump unit 22, feeds with fluid under pressure. the starter 20 via the fluid distribution unit 35. The motor 20A rotates and the starter 20 then rotates the heat engine 14. The first start line 41 at the output of the starter 20 is connected to the return tank 25 via the control line 44 and the return return line 30R. In its operating state of energy recovery, as represented in FIG. 3, the starting system 10 implements, on the one hand, the lateral diversion stage 37T and, on the other hand, the right communication stage 38T. of the bypass valve 38. Thus, the supply line 28 is in communication with the first start line 41 at the output of the starter 20 whose motor 20A operates as a pressure generator driven by the engine 14. The use of the group Electropump 22 can thus be saved. The engine 20A is supplied by the return tank 25 via the return return line 30R, the right communication stage 38T of the bypass valve 38, the control line 44, the side diversion stage 37T and the second Starting line 42. In the event of excessively high production of hydraulic pressure by the engine 20A, the pressure limiter 52 sends fluid from the first starting line 41 to the second starting line 42 for a return of fluid to the reservoir. return 25 via valve 36, line 44, valve 38 and start return line 30R.

Advantageously, the engine starting system 14 via the hydraulic starter 20 is associated with the source and / or the hydraulic power reserve which are constituted by the electric pump unit 22 and the accumulator 24 and which are intended for the Transmission automation 16 and / or clutch 18. This pooling of energy source is favorable to the simplification and reduction of the cost of the vehicle or any machine or machine using this starting system. thermal engine associated with a robotized gearbox and / or a controlled clutch.

Thus, it is advantageous to use an advantageous combination of starting with a hydraulic starter with the electrohydraulic gearbox and / or controlled clutch control systems, by sharing the hydraulic power source.

The possibility of using the hydraulic starter as energy recuperator in engine braking is an additional advantage. The starter system 10 is advantageous for use in a motor vehicle since the manufacturers have developed stop and start systems of the engine to stop it as soon as possible and limit its energy consumption. The start-up function becomes more solicited, requires reinforcement and requires increased efficiency so as not to impair the use of the vehicles. The hydraulic starter 20 meets the criteria of power, response time, compactness and robustness. The electric pump unit 22 and the accumulator 24 are able to provide the necessary hydraulic power, all the more so as to share the hydraulic power between, on the one hand, the actuation of the box and / or the clutch and on the other hand. on the other hand, starting the engine is possible since these two consumptions are not simultaneous. The variant of FIG. 4 illustrates a starter system 10 without the energy recovery function. In this case, the starter module 30 in the starter system 10 is devoid of a bypass valve and has a single selector valve 36 in its fluid dispensing unit 35. The valve 36 allows the system 10 to function. at its rest state so that the hydraulic transmission control module 19 operates, either at its starting state of the heat engine 14. The selection valve 36 is constituted by a two-position distributor and, here again, four orifices. It is actuated by an electromagnet 39A and a return spring 39B in the rest position. The first start line 41 is associated with the secondary port 20S of the engine 20A of the starter 20 and is connected to the return return line 30R for a return to the pilot return tank 25, without diversion. A check valve 30T is located on the return return line 30R for a flow of fluid made possible only from the motor 20A to the tank 25. The selection valve 36 has a feed inlet 36A connected to the feed line 28. The selection valve 36 also comprises a loopback input 36B connected by the first start line 41 to the secondary port 20S of the motor 20A of the starter 20. The selection valve 36 has a start output 36D connected by the second line of the starting 42 at the main port 20P of the engine 20A of the starter 20. The selection valve 36 finally comprises a control output 36P connected directly by a control line 44 to the hydraulic transmission control module 19. The selection valve 36 has two stages that is, a direct communication stage 137D and an inclined communication stage 137C. There is no side level of diversion. The direct communication stage 137D is provided for connecting on the one hand the supply input 36A with the control output 36P and on the other hand the loopback input 36B with the start output 36D.

The inclined communication stage 137C is able to connect the supply input 36A with the startup output 36D. The inclined communication stage 137C is intended to close the loopback input 36B and the control output 36P. The operation of the system variant 10 as shown in FIG. 4 resembles the operation of the embodiment illustrated in FIGS. 1 to 3. The start control module 34 controls the electromagnet 39A of the selection valve 36 which returns at rest by its return spring 39B. In the idle state of the variant of the starter system 10, as shown in FIG. 4, it is the direct communication stage 137D of the selection valve 36 which is used for the circulation. of fluid. Thus, when the starter module 30 is at rest, the supply line 28 is in communication with the control duct 44 which is in communication with the hydraulic transmission control module 20. The accumulator 24 and / or the electric pump group 22 thus feed the hydraulic transmission control module 19 so that the gearbox 16 and / or the clutch 18 function normally, being on the one hand supplied with hydraulic pressure and, on the other hand, driven by said module 19. The hydraulic pressure is supplied by the source constituted by the electric pump unit 22 and / or the accumulator 24, the control return line 19R returning fluid to the return tank 25 in which the electric pump unit 22 sucks. In the starting operating state of the heat engine, the starting system 10 implements the inclined communication stage 137C of the selection valve 36. Thus, the power supply line entation 28 is in communication with the second starting line 42 so that the accumulator 24 supplies hydraulic pressure to the starter 20 which ensures the rotation of the heat engine 14. The first starting line 41 at the output of the starter 20 is connected to the return tank 25 via the return return line 30R through the check valve 30T. In Figures 1 to 4, the starter 20 has its gear 20C meshing with corresponding teeth flywheel 14A. FIG. 5 shows another embodiment of the starter 20 of the starter module 30 in the starter system 10. This is an implantation of the starter 20 whose pinion 20C meshes with a pinion 55P that is rotationally fixed. With the gearbox shaft 57 of the gearbox 16. Here, the gearbox 16 has five gears for five forward gears, each gear having a pinion supported by the primary shaft 57 and a pinion supported by the shaft. Secondary 58. The gearbox is conventional 57-parallel manual shaft architecture type clutch 18. The clutch 18 is hydraulic fluid actuator. to the secondary shaft 58. driven type and actuated by a pressure, for example 55P pinion meshing with the corresponding pinion 20C of the starter 20 is fixed relative to the primary shaft 57 and this is the pinion the most large associated with this shaft, namely the fixed gear of fifth gear ratio of the vehicle incorporating the gearbox. In this way, the highest reduction ratio is used for the drive by the starter 20. When the starter system 10 is in its starting operating state of the engine 14, the starter 20 is activated on the same principle as explained in the description relating to Figures 1 to 4. The starter 20 drives the primary shaft 57 through the pinion 55P. The corresponding gear 5S of the gear of the fifth gear is not engaged with the secondary shaft 58. The heat engine 14 is driven by the starter 20 by closing the clutch 18 from the beginning of the starting phase of the starter 20, in order to couple the primary shaft 57 relative to the flywheel 14A. The clutch 18 can also be closed during startup of the starter 20 to take advantage of the inertia of the primary shaft 57 and to promote the rotation of the heat engine 14. As a variant not shown of the embodiment of FIG. 5, the starter pinion may be associated with a pinion which is fixed relative to the primary shaft and which is that of the gear of a ratio other than the last gear ratio of the forward gearbox. FIG. 6 represents another embodiment of starter 20 of starter system 10. This is an implementation of starter 20 whose pinion 20C meshes with a pinion 66P belonging to a gear ratio gear. front part of a gearbox 16 having two primary shafts and a secondary shaft. Such a gearbox is of known type and is driven by being conventionally associated with a double clutch provided with a clutch 25 associated with each primary shaft. Here, the gearbox 16 has six gears for six forward gears, each gear having a pinion supported by the secondary shaft 58 and a pinion supported by one or other of the primary shafts. The gear 66P meshing with the corresponding gear 20C of the starter 20 is fixed with respect to its primary shaft 67 and this is the largest gear of the gearbox, namely the fixed gear of 35 sixth gear ratio. of the vehicle incorporating the gearbox.

When the starting system 10 is in its starting operating state of the heat engine 14, the starter 20 is activated on the same principle as explained in the description relating to FIGS. 1 to 4. The starter 20 drives the primary shaft 67 through the pinion 66P. The corresponding gear 66S of the gear of the sixth gear is not engaged with the secondary shaft 58. The heat engine 14 is driven by the starter 20 by closing the friction means of the clutch 18 from the beginning of the start-up phase of the starter 20 or during starting of the starter 20 to take advantage of the inertia of the primary shaft 67. Advantageously, in the case of a start with meshing on a gear of the gearbox, the steering wheel motor is simplified by not requiring the presence of a ring gear for the starter. As a variant not shown in the embodiment of FIG. 6, the starter pinion can be associated with any fixed gear with respect to one of the primary shafts or with a pinion mounted idly on the secondary shaft. The starter system may include any equivalent means for providing the fluid delivery function. Thus, in a variant, the valves by distributors as described with reference to FIGS. 1 to 4 may be replaced in the fluid distribution unit by any equivalent means. The starter system 10 and its starter module 30 are applicable to any vehicle having a heat engine associated with a gearbox and a clutch, at least one of this gearbox and clutch being automated by actuators. utilizing the energy of a pressurized fluid supplied by a source of said fluid, a pressurized fluid starter utilizing the fluidic energy provided by said source of pressurized fluid. However, the starter system 10 and its starter module 30 are particularly applicable to use in a motor vehicle having a cabin receiving on the one hand an accelerator for controlling the load of the engine and on the other hand an interface of putting the engine in operating mode or in stop mode, a source of pressurized fluid, a control unit of the engine and a power train that includes the engine 14 associated with the gearbox 16 and the clutch 18 , at least one of this box and this clutch being automated by pressurized fluid actuators being associated with the transmission control module 19, in which vehicle, in running mode of the heat engine, the control unit of the thermal engine stops the engine as soon as the vehicle is stopped and restarts the engine as soon as a command on the accelerator, on the clutch or the gearbox. The starter system can be applied in particular for a land vehicle but also for other mobile or fixed uses. The starter system can be applied to all configurations associating a heat engine coupled to a gearbox via a controlled clutch, one or the other of this box or clutch being actuated by fluid means under pressure for example hydraulic means.

Claims (11)

REVENDICATIONS1. Starting system (10) for a heat engine (14) associated with a gearbox (16) and a clutch (18), at least one of this gearbox and clutch being automated by actuators using the energy of a pressurized fluid supplied by a source (22, 24) of said fluid, comprising a pressurized fluid starter (20) adapted to utilize the fluidic energy supplied by said fluid source (22, 24) under pressure and provided to be mechanically connected to the heat engine (14) for start-up, and a fluid distribution unit (35) having a fluid supply inlet (28, 36A) adapted to be fluidically connected to an outlet starting fluidic fluid 36D) fluidically connected to the starter and a transmission control output (46; 44) adapted to be fluidically connected to at least one of the gearbox (16) and the clutch (18). ). 2. System according to the preceding claim, characterized in that the starter (20) fluid under pressure comprises a motor (20A) having a main port (20P) and a secondary port (20S) which are connected by fluid connection to the fluid distribution unit (35) so that the main port can receive pressurized fluid from the startup fluid outlet (42, 36D) for the starter to start the heat engine (14). 30 3. System according to the preceding claim, characterized in that the motor (20A) of the starter (20) to pressurized fluid is a reversible motor capable on the one hand to consume energy of the pressurized fluid provided by the source of pressurized fluid, to start the heat engine (14), and on the other hand to produce pressurized fluid energy for said (42, (20) source, having a power supply for an accumulator (24) belonging to the source of fluid under pressure. 4. System according to any one of claims 2 to 3, characterized in that the motor 5 (20A) of the starter (20) fluid under pressure is a hydraulic motor. 5. System according to any one of the preceding claims, characterized in that the fluid distribution unit (35) comprises a selection valve (36) which can be in a state of rest putting in communication the input of fluid supply (28, 36A) with the transmission drive output (46; 44), for supplying one of the gearbox (16) and the clutch (18), and isolating the starter (30) of said supply input so that the starter is at a standstill, or can be in a start state of the heat engine (14) in which the fluid supply inlet (28, 36A) communicates with the starting fluidic outlet (42, 36D) for starting the heat engine. 6. System according to the preceding claim combined with claim 3, characterized in that the selection valve (36) can be in a state of energy recovery communicating on the one hand the secondary port (20S) of the engine (20A) of the starter (20) with the fluid supply inlet (28, 36A) of the fluid distribution unit (35) and on the other hand the main port (20P) of said engine with a port of return (30R) of said unit (35). 30 7. System according to the preceding claim, characterized in that the fluid distribution unit (35) comprises a bypass valve (38) which is interposed between on the one hand the selection valve (36) and secondly the transmission control output (46) 35 and the return port of said unit, which can be in a state of rest communicating via the selection valve (36) to its idle state, the power input in fluid (28, 36A) of the fluid distribution unit (35) with the transmission control output (46) and which can be in a second state placing the motor (20A) of the starter (20) in communication with the return port (30R), via the selection valve (36) which is in its starting state or in its state of energy recovery by further putting the motor (20A) of the starter in communication with the input of fluid supply (28, 36A). 8. A propulsion motor assembly comprising a heat engine (14) associated with a gearbox (16) and a clutch (18), at least one of this box and this clutch being automated by pressurized fluid actuators. being associated with a transmission control module (19) and a starting system (10) according to any one of claims 1 to 7, the transmission control output (46; 44) of which is connected by fluid connection to the module transmission control (19) and whose starter (20) is mechanically connected to the heat engine (14). 9. The assembly of claim 8, characterized in that the starter (20) is mechanically connected to the heat engine (14) having a pinion coupled to the flywheel (14A) of the engine. 10. An assembly according to claim 8, characterized in that the starter (20) is mechanically connected to the heat engine (14) having a pinion (20C) coupled to a pinion gear (55P, 66P) of the reduction ratio of the box gear (16), this gear gear ratio being engaged with a gearbox primary shaft. 11. A motor vehicle having a passenger compartment receiving on the one hand an accelerator for controlling the load of the engine (14) and on the other hand an engine engine switch-on interface in run mode or in stop mode, a source (22, 24 ) of pressurized fluid, a control unit of the heat engine and a power train assembly which is according to any one of claims 8 to 10, wherein, in operating mode of the heat engine (14), the control unit of the The engine will shut off the engine as soon as the vehicle is stopped and restart the engine as soon as a throttle, clutch or transmission is involved.