FR2843613A1 - Improved re-starting of internal combustion engine by detection of the absolute position of a component linked to crankshaft position, uses coded measuring device that gives position of engine to guide control of fuel and ignition - Google Patents

Abstract

The re-starting of the engine makes use of data on engine position obtained by a detector monitoring the position of the crankshaft or of a component linked to the crankshaft. The detector (23) is supplied from an electrical system (9) which controls re-starting, and for each detectable position returns position and direction of movement. This is used to control fuel and ignition.

Description

i The subject of the invention is a method and a device for improving the

  operation of an internal combustion engine of a vehicle during the first turns of rotation of a crankshaft, or of the first movements of displacement of pistons in cylinders, corresponding to a phase of restarting the engine intervening 5 after a phase of stopping this engine, the engine comprising at least one movable member from the crankshaft, connecting rods, pistons, a camshaft, valve lifters. Currently, to meet increasingly stringent environmental standards for pollutant emissions generated by vehicles, and in particular motor vehicles, professionals in the sector wish to improve

  engine starting conditions.

  Indeed, it is during starts (or restarts) that the pollution level is typically the highest, this coming in particular from the fact that it is necessary, to perfectly synchronize the fuel supply parameters 15 (typically injection and ignition conditions, to have a certain number of

engine revolutions.

  During these adjustment and calibration rounds, combustion is typically not

  not yet optimized because it is then managed by parameters taken "by default" and the pollution levels are then much higher than those existing during the subsequent engine operating steady state.

  And this problem becomes all the more important if one thinks, as currently, of making the engine stop in the event of prolonged stopping of the vehicle

  (traffic congestion, traffic lights, ...).

  However, under current engine operating conditions, stopping and restarting frequently brings more pollution than running the engines.

continuously.

  The object of the invention is to provide a solution to this problem of imperfect engine operation at the time of starting (or restarting) and

  to the corollary problems of pollution.

  The proposed solution generally consists in knowing the exact position of the engine (for example that of the pistons in the cylinders, or that, angular, of the crankshaft) at the time of starting, or restarting, of this one, in order to draw from it

  gone to optimize the first ignition cycles.

  In this context, the proposed solution provides in particular that: - for restarting, the position of the movable member is taken into account, just before it is driven in motion during this phase of restarting the engine, - before this restarting , the absolute position of the movable member is detected, 5 by means of a detection unit supplied with electrical energy, each detectable position, in the considered direction of movement, being therefore coded differently from the others, - and then leads the restart according to this absolute position

thus detected.

  The absolute position detection of the movable member makes it possible to overcome the possible difficulty linked to the existence of a necessary displacement (movement) of this

  movable member so that its position can be detected.

  In other words, the above solution makes it possible to know the exact position of the movable member considered of the engine when this engine starts, without necessarily having to make the engine make a few turns to have picked up the position. . This position detection (detection) can thus in particular be carried out automatically as soon as the user of the vehicle has switched on the ignition (typically by its

  ignition key) and that the general electrical system of the vehicle is energized.

  In this regard, it is also envisaged in the invention that: a) the detection unit being energized before any restart, the successive absolute positions of the movable member are detected, if the latter is then in motion , and the restart is conducted as a function of the last absolute position thus detected, b) another alternative or complementary possibility to the previous one: - the vehicle is fitted with an electrical system, the powering up, and therefore the operation, conditions everything starting or restarting of this vehicle, - and as long as this electrical system is energized, the absolute position of the movable member, as long as the latter is substantially stationary, or of its successive absolute positions, when it is in motion, is (are) detected ,. 30 c) another additional possibility, an alternative to the previous one: - the vehicle is fitted with an electrical system which intervenes in the operation of the engine and whose switching on or off is triggered by the user of the vehicle, by through a contact member, such as an ignition key, - and, if this electrical system is switched off, by switching off the ignition, detecting the absolute position of the movable member, as long as the latter is substantially immobile, or from these successive absolute positions, when it is in motion,

  resumes when the electrical system is turned on again.

  Another aspect taken into account in the invention concerns, once the data relating to the position of the mobile member to be considered has been obtained, how to conduct the operational implementation at least from the first moments of restarting. In this regard, a characteristic of the invention advises that from said detection carried out of the absolute position of the movable member to be considered for restarting, a more favorable moment and / or cylinder is determined for this restarting. than the others to create the first ignition of a mixture of fuel 10 and of oxidizer to ignite, or at least one of the first few

  ignition of the mixture during this restart phase.

  To satisfy this aspect of determining the best operating conditions, it is also also proposed that, during the engine restart phase, a command is given, depending on the position of the movable member to be considered for restarting, At least one of the following operations: electric spark at a time and / or in a cylinder defined as more favorable, closing and opening of the valves at said time and / or in said cylinder defined as more favorable, injection of an appropriate dose of fuel at said time and / or in said cylinder defined as

more favorable.

  Given the quality of the ignition conditions of the mixture which must

  be obtained taking into account the implementation of the invention during at least these first moments of restarting, another characteristic of the invention even provides that after having therefore detected the position of the movable member to be considered for restarting, the ignition of a mixture of fuel and oxidant to ignite in at least one cylinder intervenes as a function of this position, which induces a self-starting of the engine, without requiring any electric starter .

  Yet another aspect of the invention relates to how to obtain detection

  of the position to be considered of the movable member.

  For this, two solutions have been chosen more particularly: a) - the selected mobile member is equipped with means making it possible to modify the electromagnetic field coming from a transmitting unit, which is received by at least one sensor which occupies a position among two possible, depending on the magnetic field received, which depends on characteristics among: the transmission time, the frequency between two successive transmissions, the location of the field, its intensity, b) - to detect the position of the movable member : When equipping the mobile organ with a target fixed to it, moving with it and provided with an optical code which depends on the position of this organ, an optical sensor comprising a sensitive cell is located at a distance from the target to this code, - and the code is detected by the cell. With regard to the means in themselves provided for in the invention, it can be noted that the proposed device provides for the use of: - a detection unit, - and a computer on board the vehicle and connected to the detection to define ignition conditions of the mixture during the engine starting phase and trigger the implementation of these conditions in order to cause this

  inflammation, depending on the absolute detected position of said movable member.

  and the code is detected by the cell. Regarding the operation of the detection unit, this device 15 advises that the detection unit be supplied with electrical energy by a general electrical system for supplying the vehicle, the powering of which conditions restarting, so that the detection takes place automatically when this system

  general electrical power is on.

  Concerning the way of realizing the detection unit, for the sake of efficiency of this detection, reliability and cost control, some preferred solutions are

  more particularly recommended.

  In the first, the detection unit advantageously comprises: - on at least one of the movable members among the crankshaft and the camshaft, a target coded by holes, fixed to said member and moving with it, such so that at a determined position of the movable member corresponds a code, the code changing with the position, - at least one sensor sensitive to an electromagnetic emission, disposed opposite this target and having two electrical states which it occupies one or the other depending on the magnetic field received through the holes of the target, - and at least one magnetic field emitter arranged so that the

  target modifies the value of the field read by the sensor.

  In the second solution, the detection unit advantageously comprises: a target fixed to the movable member and moving with it, the target being provided with an optical code which therefore depends on the position of the movable member, - at at least one sensor placed at a distance from the target, the sensor comprising means for illuminating the target and a cell detecting the code of this target when it is illuminated, - and at least one optical fiber extending between the target and the sensor for

  illuminate the target and transmit back to the cell the code detected on the target.

  In the third solution: - the detection unit comprises a capacitive effect sensor and an electronic measurement unit, - the capacitive effect sensor comprises: a first electrically conductive part fixed to the movable member and moving with it, several second electrically conductive parts fixed in position and between which the first electrically conductive part is disposed and moves, the second electrically conductive parts each extending along a main axis transverse to the axis of movement of the movable member, the axes second electrically conductive parts being angularly separated from each other, - and the second electrically conductive parts are connected to an electronic processing unit to determine the value of the different capacities created by the relative positions occupied by said electrically conductive parts and to deduce the position thereof one of the first electrically conductive part and therefore that of

the mobile organ.

  In the fourth solution: - the movable member whose position has been detected is rotated and preferably corresponds to the crankshaft or a camshaft, - and the detection unit comprises: induction coils each wound around an axis transverse to the axis of rotation of the movable member ,. magnetic targets aligned along the axis of the movable member and successively formed in an inverted spiral, the targets being each arranged opposite a coil and being fixed to the movable member to move with it, and an electronic unit for processing connected to the terminals of the 30 windings of each of the coils, so that the electronic processing unit defines, by differential measurement of the eddy currents flowing through the coils, the angular position of the movable member relative to an angular position reference. In the fifth solution, the movable member whose position has been detected is rotated and preferably corresponds to the crankshaft or a camshaft, - and the detection unit comprises: at least one emission unit of an electromagnetic field fixed to the moving member and moving with it, the magnet being arranged with its poles aligned transversely to the axis of rotation of the moving member, at least one fixed magneto-resistive sensor, for detecting the direction of the magnetic field generated by the magnet, over a first angular sector ,. at least one Hall effect sensor occupying one of two possible positions, depending on the magnetic field generated, for detecting the direction of said magnetic field on a second angular sector, an electronic processing unit connected to the sensors, to define, on at least 10 a complete revolution of the movable member on itself, the angular orientation of the latter relative to a reference position, as a function of the data supplied by the sensors. In the sixth solution, it is provided that: the movable member whose position is detected is once again driven in a rotational movement and preferably corresponds to the crankshaft or to a camshaft, detection comprises: at least one unit for emitting an electromagnetic field fixed to the movable member and moving with it, the magnet being arranged with its poles aligned transversely to the axis of rotation of the movable member, a group of sensors among: at least two magneto-resistive sensors arranged to detect, each on an angular sector, the direction of the magnetic field generated by the magnet, so that together, these magneto-resistive sensors detect data 25 representative of the direction of the magnetic field generated by the magnet over at least one revolution carried out on itself by said movable member, at least two Hall effect sensors, each covering an angular sector and occupying a position among two possible depending on the magnetic field received, so that together they detect data representative of the direction of the magnetic field, on at least one revolution made around itself by the movable member, - and an electronic processing unit connected to the sensors, so

  that it defines, over at least one complete revolution around itself of the movable member, the angular orientation of the latter relative to a reference position, as a function of the data supplied by the sensor.

  In addition to what has just been presented, an additional aspect of the invention relates to the type of engine more particularly concerned, in particular for

  favor the self-starting situation already mentioned.

  In this context, it is therefore advisable to apply all or part of the 5 characteristics of the invention to an internal combustion and direct injection engine comprising: - the device for improving the (re) starting conditions presented above, - spark plugs in the context of a petrol engine, to create sparks which should explode in the cylinders, or preheating, on a diesel engine,

  - and injectors injecting fuel directly into the cylinder.

  An even more detailed description of the invention will now be provided with reference to the accompanying drawings in which:

  Figure 1 shows schematically some characteristic elements of a motor vehicle (the elements considered of the vehicle and their possible connection to each other having only been shown to illustrate the subject of the invention), Figure 2 shows, again very schematically , some characteristic elements of a vehicle engine, such as a motor vehicle, FIG. 3 schematically shows a crankshaft equipped with a magnetic system comprising means for modifying the ambient magnetic field and reading means, to constitute a first position detection unit usable in the context of the invention, FIG. 4 shows an embodiment of the target made of magnetic material from FIG. 3, FIG. 5 schematically shows a crankshaft equipped with an optical system comprising illumination means and reading means, to constitute a useful position detection unit isable in the context of the invention, FIG. 6 shows yet another possible embodiment of the detection unit of the invention, as well as, still diagrammatically, FIGS. 7, 8 and 10, FIG. 9 schematically showing the response curves of the effect sensor unit

  magnetic shown in figure 8.

  In Figure 1, a part of a motor vehicle 1 has been shown.

  The vehicle comprises an engine 3 and a dashboard 5. A wheel 7 of the

vehicle is shown schematically.

  A general electrical system generally identified 9 ensures the

  overall electrical operation of the vehicle.

  The contact for energizing the electrical system 9 is established by

  via a key 11 cooperating with a security lock 13, for example. 5 Other means exist, such as an electronic card solution which replaces the key.

The lock is electronic.

  The electrical system 9 comprises a battery 14.

  In FIG. 1, the battery 14 is connected to the detection unit 23 which makes it possible to

  note the position of the chosen movable member.

  This battery is also connected to the computer 15, to the front 25 and rear 27 lighting systems of the vehicle (signaling lights, lighting, indicators, etc.), to the indicator lights 29 on the dashboard and to various organs. of the engine 3. In this respect, the supply from the battery 14 of spark plugs 31a, 31b, and of a starter 33 which has, if provided, is typically (to date) 15 is schematically used for temporarily crankshaft 35 during start-up phases or

engine restart.

  The electrical system 9 (shown schematically in particular by a series of connecting lines) makes it possible in particular to operate the information processing members of the vehicle which, among other things, manage the operation of the engine 3, that of the braking, possibly of the power steering and vehicle lighting. Although in reality there are several information processing and calculation units on the vehicle, depending on the functions to be performed, all of these functions

  is for the sake of simplification, gathered in FIG. 1, within the computer 15.

  Thus, the computer 15 is connected to the engine 3 (without going into the details of the engine components concerned), to the braking system 17 acting on the wheel 7, to the power steering unit 19, linked to the direction 21 , and to the electrical contact box

of the lock 13.

  The computer 15 is also connected to the detection unit 23.

  In the following description, it will be considered that restarting the

  engine 3, that is to say the first rotational turns thereof, will be carried out taking into account the position of the crankshaft 35, although other movable members of the engine

  could have been used in place of the crankshaft.

  Thus, one could completely plan to detect the position before restarting 35 of at least one of the pistons 36, of a camshaft 38, of at least one of the connecting rods 40, or even of at least one of pushers valves 42, FIG. 2 also schematically illustrating the intake and exhaust valves (respectively 44a, 44b), and a cylinder 46 in which a spark plug 31a creates the electrical sparks necessary for igniting the fuel / oxidant mixture, since we suppose to be here on an internal combustion engine supplied with petrol, with an injector 48 which

  injects the fuel directly into the cylinder head 46 (direct injection).

  With such an engine constitution, it will in particular be possible to inject directly into the most suitable engine cylinder and / or at the most opportune time. Moreover, if the cylinder (such as 46) ready for ignition among the various cylinders, is known as provided for by the invention, then the on-board computer 15 will be able to enter into operation immediately, without having to go through the usual phases of calibration and initial measurements typical of the engines hitherto proposed and

  during which pollution is increased.

  It should even be possible to restart under the simple effect induced by the

  first combustion triggered by the candle.

  In accordance with the current typical operating mode of vehicles, the on-board computer should only be able to operate when the ignition is switched on, that is to say in the example used, once the key 11 has been turned in the lock. 13, this operation being able to trigger the power-up, and therefore the setting in state of

  function, from the detection unit 23.

  This does not in principle interfere with anything, as long as the detection concerns a measurement

  "absolute" of the position of the movable member. Whether the organ moves or not, its position report is accessible. Thus, this position will necessarily have been detected before any (re) start. If the organ has moved during the stop phase or is moving when the contact is restored (speed engaged for example), the position detector picks it up and the information previously stored in memory is updated.

  However, an autonomous power supply may also have been provided to allow the detection unit 23 to operate even when the ignition is off, that is to say in particular that when the user of the vehicle has parked it for a moment and left it after having locked it, or is still inside, but engine 30 switched off and ignition key in "off" position, ie all electrical contact

  is cut with regard to the electrical system 9.

  The power supply autonomy of the detection unit 23 can

  in particular be carried out by independent connection to the battery 14 (connection line 37), or even by an additional energy source 39 (additional battery 35, for example), independent of the main battery 14.

  In its very schematic representation of FIG. 1, the detection unit 23 comprises a sensor unit identified as a whole 41 operating in conjunction with a target unit identified as a whole 43 fixed to the movable member considered

  (in the example, the crankshaft 35) and therefore moving with it.

  In Figure 3, we find these parts.

  The target 43 is shown in more detail in FIG. 4.

  It is a target coded by holes or slots 45 which pass through any

  the thickness of the disc, as shown.

  This disc is fixed to the crankshaft 35, coaxial with its axis of rotation 35a

  and therefore rotates at the same time as the crankshaft.

  In front of this disc is a succession of sensors materialized by the sensor unit 41. Depending on the rotation of the crankshaft, these sensors are located

or not facing the holes in the disc.

  The sensors are of the Hall effect type, of the "Switch" type, that is to say that they can occupy one or other of two positions (high or low states) depending on the magnetic field emitted. by one or more field emitters, such as the line of fixed magnets 47, arranged behind the target 43, so that depending on the

  rotation of the crankshaft, and therefore of the disc 43, a variable magnetic field is emitted in the direction of the sensor system 41 and detected. A possible variant consists in placing one or more magnets 47 (a unit for emitting a magnetic field in general) on the side of the sensor (s) 41 and no longer behind the target 43. The movement 20 of the target 43 then modifies the magnetic field seen by the sensor (s) 41.

  Thus, depending on their position (whether or not facing a hole 45), the sensors more or less capture the magnetic field and therefore establish themselves in one of their two electrical output states, depending on whether one is below or above their tipping threshold. Thanks to this, we obtain a "digital word" generated by the high states or

  bottom of the sensors, i.e. the equivalent of a binary code.

  The accuracy of the measurements directly depends on the number of effect cells

  Hall used (each cell representing a bit).

  The binary code of the word considered is representative of the angular position of the crankshaft.

  In practice, the conformation of the target 43 will depend on the number of cylinders

  of the motor and the desired degree of precision in the displacement measurement.

  In FIG. 5, we have again very roughly schematized the

crankshaft in 35.

  Another target 43 ′ is mounted on the axis of this crankshaft, here with an optical code, such as a bar code or a color code, with different colors.

  for each angular sector corresponding to the desired measurement accuracy.

  This code is read by a reading cell 51 corresponding to a sensor

  optical, the illumination of the target 43 ′ can be carried out by a laser 53.

  Processing of the data received by the sensor 51 after illumination of the target by the laser can be carried out in a processing / calculation unit 55 where the data representative of the angular position of the crankshaft can be determined. It will also be noted that in order to read the optical code on the disk 43 ′, it is advisable to use an optical fiber 57 making it possible to place the members 51, 53 and 55 at a distance from the target, the optical readers being typically sensitive to

  temperatures above about 85 C.

  In FIG. 6, a detection system of the capacitive effect sensor type is

associated with crankshaft 35.

  More precisely, at the end of the crankshaft, still along the axis 35a of it, is fixedly mounted a conductive metal part, or electrode, 58.

  The electrode 58 rotates between two other fixed conductive metal parts 15, 59 and 61.

  The metal parts 58, 59 and 61 constitute capacitors (capacitive effect) and the value of the capacitance is proportional to the area of the capacitor formed. An associated processing electronics, shown diagrammatically at 63 and connected to the electrodes 59, 61, makes it possible to interpret the value of the different capacities created by this

  electrode system for providing the absolute angular position of electrode 58.

  The offset of 90 between the two electrodes 59 and 61 makes it possible to determine the exact position on 360 of the mobile electrode 58. Each of these electrodes is presented here as an angular sector, in this case a half disc, the two half 25 discs being parallel to each other and therefore angularly offset by 90 to one another, in the figure.

  The solution illustrated in Figure 7 uses an eddy current sensor. Two coils 65, 67, in the form of two discs with axes parallel to each other but perpendicular to the axis 35a of the crankshaft are placed radially opposite

  of two magnetic targets 69, 71, in the form of inverted spirals fixed on the shaft 35.

  As in many of the other cases, targets 69 and 71 can be

  arranged either at one end, or possibly in the intermediate part, of the bearing member concerned, in this case the crankshaft. The targets are arranged with their winding axis 35 coinciding with the axis 35a.

  According to the position of the spirals (therefore according to the value of the air gaps seen by

  coils), the effect of the eddy current is more or less important.

  By differential measurement of these currents through the coils and with a suitable electronic circuit provided in the associated processing unit 73 connected to the

  coils, we can know the absolute position of the shaft 35.

  A single coil could suffice, but the system would then be sensitive to air gap variations (due for example to thermal expansion). Thanks to the use of two coils and a differential measurement via the

  treatment 73, these possible problems are effectively freed.

  In FIG. 8, it is a solution with magnetic effect sensors which is

  considered, with a magneto-resistive sensor combined with one or two Hall effect "Switch" sensors.

  One possibility is thus to capture, with a magneto-resistive sensor 75, the direction of the magnetic field generated by a magnetic system 77 (magnet whose poles have been schematized south S and north N), fixed coaxially to the crankshaft and therefore rotating

  with it (see axis 35a and rotation arrow 79).

  We get an exit sign depending on the direction of the field

magnetic on 180.

  In order to extend the measurement over an interval of 360, this first measurement can be combined with a Hall effect "Switch" cell, 81, consisting for example of a "Hall 805" sensor from the company "Micronas" or even two cells 81, 83 20 offset angularly, by a few degrees, in order to solve the problems

  hysteresis of the first cell.

  The Hall effect "Switch" cells (also called a Hall switch probe) occupy one or the other of two possible positions, as indicated above. However, tilting from a position is not immediate and some hysteresis typically occurs in tilting. The hysteresis is nevertheless quite weak and in order to completely overcome it, two offset cells

  angularly a few degrees are enough.

  Data from these measurements is processed by a unit

  processing electronics not shown.

  Figure 9 shows schematically as a function of the angle of rotation of the crankshaft the evolution of the output signals, respectively of the magnetoresistive sensor 75 (top curve), and of the two Hall effect sensors 81, 83 (respectively intermediate curves

and bottom).

  In FIG. 10, a solution has two linear sensors of the Hall effect “Switch” type, which could be replaced by two linear sensors of the GMR (Giant) type.

Magneto Resistive), is illustrated.

  We can thus plan to work, as an alternative to the other solutions, with linear Hall or GMR sensors or cells which can be coaxially fixed to the

crankshaft 35.

  The sensors are respectively marked 85 and 87 in FIG. 10. They are offset axially and angularly relative to the magnet system 89 which is arranged with its poles perpendicular to the axis 35a of rotation of the movable member.

  The output voltage across each Hall or GMR sensor gives

  directly the value of the measured magnetic field.

  The magnetic field generated then provides a sinusodal signal and therefore an identification of the angular position of the part 35, to within 180 C.

  The second sensor measures another component of the magnetic field,

  thus allowing the measurement to be extended to 360.

  Measurement / processing electronics (not shown) are

  advantageously associated with the sensors for processing the signal to be transmitted with a view to restarting.

  Instead of being mounted axially (here crankshaft axis), some of the previous detection systems could be mounted radially (see that of the

Figure 5, for example).

  Furthermore, although not shown in FIGS. 3, 8 and 10, processing electronics are advantageously associated with the sensors provided in these figures.

Claims (17)

  1.- Method for improving the operation of an internal combustion engine of a vehicle, during the first rotational turns of a crankshaft (35), or the first movements of displacement of pistons (36) in cylinders (46 ), corresponding to a phase of restarting the engine intervening after a phase of stopping this engine, the engine comprising at least one movable member (35 ...) among said crankshaft, connecting rods, pistons, a camshaft (38), valve lifters, the method comprising steps in which: - for restarting, the position of the movable member is taken into account, just before it is driven in motion during this phase of restarting the engine , 10 before this restart, the absolute position of the movable member is detected, by means of a detection unit (23) supplied with electrical energy, each detectable position, in the considered direction of movement, being coded for this différemme nt others,   - And the restart is then carried out as a function of this absolute position thus detected.   2.- Method according to claim 1, characterized in that, the detection unit (23) being energized before any restart, the successive absolute positions of the movable member (35 ...) are detected, if this is then in motion, and the restart is conducted as a function of the last absolute position thus detected. 3. Method according to claim 1 or 2, characterized in that: - the vehicle is equipped with an electrical system (9), the powering up, and therefore the operation, conditions any starting or restarting of this vehicle, - and as long as this electrical system is energized, the absolute position of   the movable member (35 ...), as long as the latter is substantially stationary, or from its successive absolute positions, when it is in motion, is (are) detected.   4.- Method according to claim 1 or 2, characterized in that: - the vehicle is equipped with an electrical system (9) which intervenes in the operation of the engine and whose switching on or off is triggered by the vehicle user, via a contact member (11), such as an ignition key, - and, if this electrical system is switched off, by switching off the ignition, detecting the absolute position of the movable member (35 ...), as long as the latter is substantially stationary, or of these successive absolute positions, when it is in   movement, resumes when the electrical system is energized.   5.- Method according to one of claims 1 to 4, characterized in that from   the detection of the absolute position of the movable member (35 ...) to be considered for restarting, a moment and / or a cylinder (46) more favorable than the others is determined for this restarting to create the first inflammation a mixture of fuel and oxidizer to ignite, or at least one of the first few   ignition of the mixture during this restart phase.   6.- Method according to any one of the preceding claims, characterized   in that after detection of the absolute position of the movable member (35 ...) to be considered for restarting, the ignition of a mixture of fuel and oxidant to be ignited in at least one cylinder (46) occurs as a function of this position, which induces starting of the engine, without the need to request an electric starter (33). 7. - Method according to any one of claims 1 to 5, characterized in that   that, during the engine restart phase, at least one of the following operations is controlled, depending on the position of the movable member (35, etc.) to be considered for restarting: electric spark at a time and / or in a cylinder (46) defined as more favorable, closing and opening of the valves (44a, 44b) at said time and / or in said cylinder defined as more favorable, injection of an appropriate dose of   fuel at said time and / or in said cylinder defined as more favorable.   8.- Method according to any one of the preceding claims, characterized   in that, to detect the position of the movable member, the movable member (35 ...) is equipped with a unit for the selective emission of an electromagnetic field (47), which is received by at least 20 a sensor (41) which occupies one of two possible positions, depending on the magnetic field received, which depends on characteristics among: the transmission time,   the frequency between two successive transmissions, the location of the field, its intensity.   9.- Method according to any one of claims 1 to 7, characterized in that   that: - to detect the position of the mobile organ: the mobile organ is equipped with a target (43 ') fixed to it, moving with it and provided with an optical code which depends on the position of this organ , an optical sensor (51) comprising a cell sensitive to this code is located at a distance from the target,   - and the code is detected by the cell.   10.- Device for improving the operation of an internal combustion engine of a vehicle, during the first rotational turns of a crankshaft (35), or the first movements of displacement of pistons (36) in cylinders (46 ), corresponding to a phase of restarting the engine intervening after a phase 35 of stopping this engine, the engine comprising at least one movable member (35 ...) among said crankshaft, connecting rods, pistons, a camshaft (38), valve lifters, the device comprising, so that during restarting, the position of the movable member is taken into account, just before it is driven in motion during this phase of restarting the engine: - a unit position detection sensor (23, 41) adapted to detect the absolute position of at least one of the movable members (35 ...) before this restart, - and a computer (15) on board the vehicle and connected to the unit detection to define ignition conditions d u mixing during the engine start-up phase and trigger the implementation of these conditions in order to cause this   inflammation, depending on the absolute detected position of said movable member.   11.- Device according to claim 10, characterized in that the detection unit (23) is supplied with electrical energy by a general electrical system (9) for supplying the vehicle, the energization of which conditions restarting, so that detection takes place automatically when this general electrical system is on.   12.- Device according to one of claims 10 or 11, characterized in that the detection unit comprises:   - on at least one of the movable members (35 ...) among the crankshaft and the camshaft, a target (43) coded by holes (45), fixed to said member and moving with it, such so that at a determined position of the movable member corresponds a code, the code changing with the position, - at least one sensor (41) sensitive to an electromagnetic emission, arranged opposite this target and having two electrical states which it occupies one or the other depending on the magnetic field received through the holes in the target,   - And at least one magnetic field emitter (47).   13.- Device according to claim 10 or 11, characterized in that the detection unit comprises: - a target (43 ') fixed to the movable member and moving with it, the target being provided with a code optics which therefore depends on the position of the movable member, - at least one sensor (51, 53) disposed at a distance from the target, the sensor comprising means (53) for illuminating the target and a cell (51) detecting the code of this target when it is illuminated, - and at least one optical fiber (57) extending between the target and the sensor for   illuminate the target and transmit back to the cell the code detected on the target.   14.- Device according to any one of claims 10 or 11, characterized   in that: - the detection unit comprises a capacitive effect sensor and an electronic processing unit (63), - the capacitive effect sensor comprises: a first electrically conductive part (58) fixed to the movable member (35 ...) and moving with it, several second electrically conductive parts (59, 61) fixed in position and between which is disposed and moves the first electrically conductive part 5, the second electrically conductive parts each extending along an axis main transverse to the axis of movement of the movable member, the axes of the second electrically conductive parts being angularly separated from each other, and the second electrically conductive parts are connected to the electronic processing unit (63) to determine the value of the different capacities created by the relative positions occupied by said electrically conductive parts and for deduce the position of the first part electrically   conductive and therefore that of the movable member.   15.- Device according to any one of claims 10 or 11, characterized in that:   the movable member whose position has been detected is rotated and preferably corresponds to the crankshaft (35) or to a camshaft (38), and the detection unit comprises: coils of induction (65, 67) each wound around an axis 20 transverse to the axis of rotation of the movable member, magnetic targets (69, 71) aligned along the axis of the movable member and successively formed in a spiral inverted, the targets being each arranged opposite a coil and being fixed to the movable member to move with it, and an electronic processing unit (73) connected to the terminals of the windings of each of the coils, so that the 'electronic processing unit defines, by differential measurement of the eddy currents flowing through the coils, the angular position of the movable member with respect to a reference angular position.   16.- Device according to any one of claims 10 or 11, characterized   in that: - the movable member whose position has been detected is rotated and preferably corresponds to the crankshaft (35) or to a camshaft (38), - and the detection unit comprises: 35. at least one magnet (77) fixed to the movable member and moving with it, the magnet being arranged with its blades aligned transversely to the axis of rotation (35a) of the movable member, at least one sensor fixed magneto-resistive (81, 83), to detect the direction of the magnetic field generated by the magnet, on a first angular sector, at least one Hall effect sensor (75) occupying one of two possible positions, depending on the field magnetic field, to detect the direction of said magnetic field on a second angular sector ,. an electronic processing unit connected to the sensors, to define, over at least one complete turn on itself of the movable member, the angular orientation of the latter relative to a reference position, according to the data provided by the sensors.   17.- Device according to any one of claims 10 or 11, characterized   in that: the movable member whose position has been detected is rotated and preferably corresponds to the crankshaft (35) or to a camshaft (38), and the detection unit comprises: 15. at least one magnet (89) fixed to the movable member and moving with it, the magnet being arranged with its poles aligned transversely to the axis of rotation of the movable member, a group of sensors among: at at least two magneto-resistive sensors arranged to detect, each on an angular sector, the direction of the magnetic field generated by the magnet, so that together, these magneto-resistive sensors detect data representative of the direction of the magnetic field generated by the magnet on at least one revolution carried out on itself by said movable member, at least two Hall effect sensors (85, 87), each covering an angular sector and occupying one of two possible positions depending on the field magnetic received, so that together, they detect data representative of the direction of the magnetic field, on at least one revolution carried out around itself by the movable member, - and an electronic processing unit connected to the sensors, so 30 that it define, on at least one complete turn around itself of the movable member, the angular orientation of the latter relative to a reference position, as a function of the data provided by the sensor.   18.- Application of the device according to one of claims 10 to 17, to a   petrol engine with direct injection in which, as a function of the position taken into account of the movable member at the time of restarting, the ignition of the mixture in at least one cylinder occurs, which induces starting of the engine, without we have to   apply for electric starter.   19.-Internal combustion engine and direct injection of fuel into engine cylinders, the latter comprising:   - the device according to any one of claims 10 to 17,   - spark plugs (31a, 31b) in the context of a petrol engine, to create sparks which should explode in the cylinders, or of preheating, on a diesel engine,   - And injectors (48) injecting the fuel directly into the cylinders.