EP0010033B1 - Angular position sensor for an internal combustion engine fitted with an electronic ignition system - Google Patents

Abstract

An internal combustion engine with M cylinders having an electronic ignition system, a pistons position sensor having a set of M+1 identical conductive members, which are synchronous with rotation of the engine's crankshaft. M of the conductive members are regularly spaced. Two fixed detectors adjacent the rotating members sense the members and supply identical electrical signals. The detectors are spaced to provide the signals out of phase by an amount that is substantially higher than the maximum ignition advance of the engine. Electronic circuits process the signals from the two detectors, include a first circuit that supplies a synchronization signal for the cycle igniting the engine, and a second circuit, which supplies two representative synchronization signals of the static advance and of the maximum dynamic advance during ignition.

Description

The invention relates to the technique of ignition of multi-cylinder internal combustion engines; more specifically, it relates to an angular position sensor which provides a plurality of electrical signals allowing the synchronization of an electronic ignition system.

An electronic ignition system, for an internal combustion engine comprising a plurality of cylinders, comprises: automatic advance circuits which, at a determined instant, depend on the engine operating speed, electrical signals making it possible to trigger sequentially tily, via a distribution circuit, spark generators being connected to the spark plugs arranged in the engine cylinders.

In an electronic ignition system, it is known, in order to ensure perfect operation of the automatic advance circuits over all of the engine operating regimes, to implement automatic advance circuits comprising two channels whose operation is mutually exclusive; a first channel which operates during the engine starting and idling phases, and a second channel which operates during the cruising phase. It is also known, in order to reduce the number of spark generators by a factor of two, to use spark generators with twin secondary.

• - une première série de signaux qui indique les instants de passage des pistons en un point voisin du Point Mort Haut (PMH):
• - une seconde série de signaux identiques à la première série; le déphasage relatif entre la première et cette seconde série étant au moins égal à l'angle d'avance maximal à commander;
• - une troisième série de signaux qui permettent, de façon cyclique, le déclenchement séquentiel de générateurs d'étincelles à secondaire jumelé ou non.

To ensure the synchronization of an ignition system, comprising in particular: automatic advance ignition circuits of the double channel type and a distribution circuit connected to a plurality of spark generators, it is necessary to have available '' a piston position sensor, or angular position sensor, which provides three series of synchronous electrical signals of engine rotation:

• - a first series of signals which indicates the instants of passage of the pistons at a point close to Top Dead Center (TDC):
• - a second series of signals identical to the first series; the relative phase shift between the first and this second series being at least equal to the maximum feed angle to be controlled;
• - a third series of signals which allow, in a cyclic manner, the sequential triggering of spark generators with secondary, whether or not twinned.

In addition, it may be noted that it is desirable to be able to produce, from one or a combination of these series of signals: a continuous signal proportional to the speed of rotation N of the motor, and possibly signals with two states indicating the engine rotation speeds, for example starting, idling, cruising and overspeed or even a set speed.

We already know, from FR-A-2,374,528, a sensor for measuring the position of the pistons, coupled to an output axis of the engine; this sensor delivers three series of electrical signals having the characteristics listed above. In this sensor, of the prior art, metal weights are placed on a disc driven in rotation by the motor, a pair of angularly offset detectors detects the passage of the weights and provides two series of electrical signals which are combined, in a circuit coincidence, for the purpose of providing reference signals for the engine ignition cycle. In this type of sensor, there are two sets of weights: a first set of weights made up of short metal segments and a second set of weights made up of long metal segments, the arc of which is at least equal to the maximum angle in advance to order.

A disadvantage of this sensor lies in the fact that, when the diameter of the circle, on which these weights are positioned is large, and that the feed angle to be controlled is large, therefore correlatively the length of the segments of the second set of weights then, at high speeds of rotation of the engine, this second set of weights is subjected to excessive mechanical breakout forces.

Also, the object of the invention is to remedy the aforementioned defect by providing a sensor for measuring the position of the pistons, in which all the metal weights are identical and of small dimensions.

Thus appears a first advantage of the sensor according to the invention, in which the low mass of the weights allows their positioning on a circle of large diameter.

A second advantage results from the fact that the identity of the weights simplifies the problems of large series production.

The present invention also relates to a sensor, the electro-mechanical components of which can be easily integrated into the engine, in that the weights can be arranged, for example, by simple fixing means, on the flywheel of the engine or the disc. clutch, and in that the pair of detectors can be mounted in the thickness of the flywheel or clutch protection casing.

According to the invention, a sensor for measuring the position of the pistons of a multi-cylinder internal combustion engine equipped with an electronic system for igniting the air / fuel mixture admitted into the cylinders, comprising electronic circuits for automatic advance double channel type an electronic distributor and spark generators connected to the spark plugs, includes: electromechanical means, coupled mechanically to an output axis of the engine, providing electrical signals representative of the position of the pistons of the engine, and electronic means for processing these output signals providing synchronization signals of the electronic ignition system; this electromechanical means comprises: a set of M + 1 conducting weights, all identical and of small dimensions, driven in rotation by the engine crankshaft, and two fixed detectors, arranged opposite the travel of the weights, which deliver two identical electrical signals and phase shifted between them by a determined quantity, and, the electronic means comprises: a coincidence logic circuit which combines the output signals of the two detectors to provide an output signal corresponding to the ignition cycle of the engine, and a first and a second logic circuit each connected to the output of the coincidence logic circuit on the one hand and to the output of the corresponding detector on the other hand and respectively providing an output signal corresponding to the instants of passage of the pistons in the vicinity of the TDC of the pistons in engine cylinders and an output signal. corresponding to the instants of passage of the pistons at a point before TDC of the pistons in the engine cylinders; the set of M + 1 conducting weights comprises M main weights regularly spaced angularly and one (1) auxiliary weights offset angularly with respect to one of the main weights by an angle φ _D , at least equal to the angle O _A d maximum advance to engine ignition.

Other characteristics and advantages which the invention provides will appear in the detailed description which follows, given with reference to the appended drawings which represent, by way of explanation but in no way limitative, embodiments of the invention.

• la Figure la représente, sous la forme d'un schéma fonctionnel, un capteur de position angulaire de l'art antérieur;

• - la figure 1 b représente les chronogrammes des signaux de sortie fournis par le capteur de la figure 1 a;
• - la Figure 2a représente, sous la forme d'un schéma fonctionnel, un capteur de position angulaire, selon l'invention;
• - la Figure 2b représente les chronogrammes des signaux élaborés et fournis par un capteur de position angulaire, selon l'invention;
• - la Figure 3a représente, sous la forme d'un schéma fonctionnel, un mode de réalisation des moyens électroniques d'un capteur de position angulaire selon l'invention;
• - les Figures 3b et 3c représentent les chronogrammes des signaux électriques élaborés par les moyens electroniques;
• -la Figure 4 représente, en vue latérale, un mode de réalisation d'un détecteur;
• - la Figure 5 représente, sous la forme d'un schéma fonctionnel, un exemple d'application d'un capteur selon l'invention à un moteur quatre cylindres équipé d'un système d'allumage électronique.
• - la Figure 6 représente, sous une forme schématique, la configuration des moyens électromécaniques d'un capteur destiné à un moteur comportant trois groupes de deux cylindres;
• - la Figure 7 représente, sous une forme schématique, la configuration des moyens mécaniques d'un capteur dont les masselottes sont entraînées en rotation par l'arbre de distribution du moteur.
• - la Figure 8 représente, sous la forme d'une courbe, une foi typique d'avance à l'allumage, en fonction de la vitesse de rotation du moteur,
• - la Figure 9 représente, sous la forme d'un schéma synoptique simplifié, une variante de réalisation du capteur de position angulaire représenté sur la figure 2a.
• - la Figure 10 représente les chronogrammes des principaux signaux électriques associés au capteur représenté sur la figure 9,
• - la Figure 11 représente, sous la forme d'un schéma électrique, un mode de réalisation des circuits électroniques, de traitement du capteur représenté sur la Figure 9,
• --la Figure 12 représente sous la forme d'un schéma synoptique, une variante de réalisation du système électronique d'allumage équipé d'un capteur de position angulaire, selon l'invention,
• - la Figure 13 représente, sous la forme d'un schéma électrique, un mode de réalisation des circuits électroniques permettant d'inhiber les signaux parasites résultant du rayonnement électromagnétique des générateurs d'étincelles.

In these drawings:

• Figure la shows, in the form of a block diagram, an angular position sensor of the prior art;

• - Figure 1b shows the timing diagrams of the output signals supplied by the sensor of Figure 1a;
• - Figure 2a shows, in the form of a block diagram, an angular position sensor, according to the invention;
• - Figure 2b shows the timing diagrams of the signals produced and supplied by an angular position sensor, according to the invention;
• - Figure 3a shows, in the form of a block diagram, an embodiment of the electronic means of an angular position sensor according to the invention;
• - Figures 3b and 3c show the timing diagrams of the electrical signals produced by electronic means;
• FIG. 4 represents, in side view, an embodiment of a detector;
• - Figure 5 shows, in the form of a block diagram, an example of application of a sensor according to the invention to a four-cylinder engine equipped with an electronic ignition system.
• - Figure 6 shows, in schematic form, the configuration of the electromechanical means of a sensor intended for an engine comprising three groups of two cylinders;
• - Figure 7 shows, in schematic form, the configuration of the mechanical means of a sensor whose weights are rotated by the engine timing shaft.
• FIG. 8 represents, in the form of a curve, a typical faith of ignition advance, as a function of the engine rotation speed,
• - Figure 9 shows, in the form of a simplified block diagram, an alternative embodiment of the angular position sensor shown in Figure 2a.
• FIG. 10 represents the timing diagrams of the main electrical signals associated with the sensor represented in FIG. 9,
• FIG. 11 represents, in the form of an electrical diagram, an embodiment of the electronic circuits, for processing the sensor shown in FIG. 9,
• FIG. 12 represents, in the form of a block diagram, an alternative embodiment of the electronic ignition system equipped with an angular position sensor, according to the invention,
• - Figure 13 shows, in the form of an electrical diagram, an embodiment of the electronic circuits making it possible to inhibit the parasitic signals resulting from the electromagnetic radiation of the spark generators.

In the description which follows, it will be considered that the basic knowledge relating to multi-cylinder internal combustion engines is widely available in the available technical works.

• - un disque C entraîné en rotation autour d'un axe central 0, par le vilebrequin du moteur; sur la périphérie de ce disque sont disposées deux masselottes métalliques, une masselotte M1 d'arc φ₁ et une masselotte M2 d'arc φ₂; l'espacement angulaire entre les masselottes M1 et M2 étant égal à 180°;
• - un couple de détecteurs fixes; un détecteur D1 et un détecteur D2 disposés en regard de la course des masselottes M1 et M2, l'espacement angulaire relatif entre ces deux détecteurs étant égal à un arc φ_D; le détecteur D1 fournit un signal de sortie E1 et le détecteur D2 fournit un signal de sortie E2.
• - un circuit électronique de coïncidence comportant deux entrées: une première entrée reliée à la sortie du détecteur D1 et une seconde entrée reliée à la sortie du détecteur D2; ce circuit électronique fournit un signal de sortie E_o.

Figure 1a shows, in a simplified schematic form, a sensor of the prior art, intended to equip an engine which comprises two groups of two cylinders associated with two spark generators with twin secondary. This sensor essentially comprises:

• - a disc C driven in rotation about a central axis 0, by the engine crankshaft; on the periphery of this disc are arranged two metal weights, a weight M1 of arc φ ₁ and a weight M2 of arc φ ₂ ; the angular spacing between the weights M1 and M2 being equal to 180 °;
• - a couple of fixed detectors; a detector D1 and a detector D2 arranged opposite the travel of the weights M1 and M2, the relative angular spacing between these two detectors being equal to an arc φ _D ; the detector D1 provides an output signal E1 and the detector D2 provides an output signal E2.
• - an electronic coincidence circuit comprising two inputs: a first input connected to the output of the detector D1 and a second input connected to the output of the detector D2; this electronic circuit provides an output signal E _o .

By construction, the relative angular spacing φ _D of the two detectors has a value greater than the maximum advance angle φ _A to be controlled; the value of the arc φ ₁ is less than the value φ _D and the value of the arc 0 ₂ is greater than the value φ _D ; the direction of rotation of the disc C is indicated by the arrow; means being provided to ensure the relative angular setting between the disc C and the pair of detectors D1 and D2.

FIG. 1b represents the timing diagrams of the output signals of the sensor of FIG. 1 a. It may be recalled that an ignition cycle of the engine corresponds to two revolutions of the crankshaft, consequently, a complete ignition cycle corresponds to a rotation of 720 ° of the disc C.

In FIG. 1b, the signal E2, considered during an ignition cycle, consists of two slots 2 corresponding to the passage of the counterweight M2 in front of the detector D2 and two slots 1 corresponding to the passage of the counterweight M1 in front of the detector D2.

The signal E1 is constituted by a sequence of identical slots 1 ′, 2 ′, with slots 1,2, this sequence being phase shifted late by an angle φ _D. The EO signal results from the logical conjunction of the E1 and E2 signals. The rising edges of the signals E1 and E2 define the instants of synchronization of the automatic advance circuit and the falling edges of the signal EO can be used to synchronize a distribution circuit of signals for triggering the spark generators.

In FIG. 1b have been indicated in dotted lines the TDC marks which are located in the vicinity of the rising edges of the signal E1; the phase shift between the TDCs and the rising edges of the signal E1 being equal to the angle 5 of static setting.

• - des moyens électromécaniques 105a comprenant trois masselottes identiques: deux masselottes principales: une masselotte M1 et une masselotte M2 diamétralement opposées et une masselotte auxiliaire Mα indentique aux masselottes M1 et M2, cette masselotte Ma étant décalée angulairement par rapport à la masselotte M2 d'un arc φ_D; un couple de détecteurs D1 et D2 fixes, dont l'espacement relatif est égal à l'angle φ_D déjà défini.
• - des moyens électroniques 105b comprenant trois circuits: un circuit logique de coïncidence 110 comportant deux entrées: une première entrée reliée à la sortie du détecteur D1 et une seconde entrée connectée au détecteur D2; un premier circuit logique 120 comportant également deux entrées, une première entrée reliée à la sortie du détecteur D1 et une seconde sortie reliée à la sortie du circuit logique de coïncidence 110, enfin un second circuit logique 130, comportant également deux entrées, une première entrée reliée à la sortie du détecteur D2 et une seconde entrée reliée à la sortie du circuit logique de coïncidence 110.

FIG. 2a represents, in a functional schematic form, a sensor, in accordance with the invention, intended to equip an engine comprising two groups of two cylinders, each of these groups being supplied by a spark generator with twin secondary; this sensor, in accordance with the invention, comprises:

• electromechanical means 105a comprising three identical counterweights: two main counterweights: a diametrically opposed counterweight M1 and an M2 counterweight and an auxiliary counterweight Mα identical to the counterweights M1 and M2, this counterweight Ma being angularly offset with respect to the counterweight M2 arc φ _D ; a pair of fixed detectors D1 and D2, the relative spacing of which is equal to the angle φ _D already defined.
• - Electronic means 105b comprising three circuits: a coincidence logic circuit 110 comprising two inputs: a first input connected to the output of the detector D1 and a second input connected to the detector D2; a first logic circuit 120 also comprising two inputs, a first input connected to the output of the detector D1 and a second output connected to the output of the coincidence logic circuit 110, finally a second logic circuit 130, also comprising two inputs, a first input connected to the output of detector D2 and a second input connected to the output of the coincidence logic 110.

In FIG. 2a, the three weights M1, M2 and Ma are arranged, by means of fixing means, on a rotating element V, driven in direct engagement by the axis A of the engine crankshaft, for example, the rotating element may be constituted by the engine flywheel. The detector coupler D1 and D2 is arranged in the thickness of a housing B, this housing B or fixed element may be constituted by the protective casing of the steering wheel, partially shown in this FIG. 2a. The electrical output signals from the detectors D1 and D2 are respectively the signals E1 and E2, and the output signals from the circuits 110, 120 and 130 are respectively the signals S0, S1 and S2.

Figure 2b shows the timing diagrams of the main sensor signals of Figure 2a, considered during an engine ignition cycle. The signal E2 is formed by the sequence of signals in slots 2, a and 1 resulting from the passage of the weights M2, Mα and M1 in front of the detector D2. The signal E1 is formed by the sequence of the signals 2 ', a' and 1 ', resulting from the passage of the respective weights M2, Mα and M1 in front of the detector D1. The signal SO results from the logical conjunction of the signals E1 and E2, while the signal S2, produced by the circuit 120 results from the logical combination of the signals E2 and SO and the signal S1, produced by the circuit 130, results from the combination logic of signals E1 and S0. The rising edges of the signals S1 and S2 make it possible to synchronize the automatic advance circuits and the falling edges of the signal SO make it possible to synchronize the distribution circuit of the triggering signals of the spark generator.

The repetition frequency of the signals generated by the sensor being proportional to the speed of rotation N of the motor, these signals can be used to develop a signal representative of the speed of rotation N; the relative phase of the signals E1 and E2 generated by the sensor can, if necessary, be used to determine the different engine rotation regimes. In this figure, the angle of static ignition timing is indicated with a negative value; it should however be understood that the magnitude of this angle δ can be zero, positive or negative.

By construction, depending on the type of engine considered, the weights and the detectors can be positioned so as to meet the ignition timing conditions, so such a sensor does not necessarily require auxiliary timing means. In FIG. 2a, the weights have been represented under the shape of arc segments, however, other forms of weights are possible, for example cylindrical, with or without flats. The means of fixing these weights can be constituted by a threaded element which screws into the thickness of the mass of the steering wheel. The metal weights can be made of a metal of the same kind as that of which the rotating element on which these weights are arranged is made. The magnitude of the arc φ ₁ can be a few degrees, and the magnitude of the angle φ _D several tens of degrees, with an extreme value of 90 ° in the example of embodiment described. In practice, the diameter of the element V is between 150 and 300 mm.

FIG. 3a represents, in functional form, an embodiment of the logic circuits 110, 120 and 130 represented in FIG. 2a, and FIGS. 3b and 3c represent timing diagrams of the main input / output signals of the components of FIG. 3a.

In this FIG. 3a, the coincidence logic circuit 110 is constituted by a logic gate 11 of the "NAND" type (NAND according to the Anglo-Saxon convention) with two inputs: a first input which receives the output signal È1 from the detector D1 and a second input which receives the output signal E2 from the detector D2; the output of this gate is complemented by an inverter 112 whose output signal is the signal S0.

The logic circuit 120 comprises the following components: an inverter 121, two flip-flops 122 and 123, a logic gate 124 of the "NO OR" type (NOR according to the Anglo-Saxon convention) and an inverter 125. The operation of this circuit 120 will now be described with reference to FIG. 3b. The rising edge of the signal S0, applied to the input S of the flip-flop 122, positions the output Q ₁₂₂ at the high level; the falling edge of the signal E1.α complemented by the inverter 121 is applied to the input C of the flip-flop 122 and samples the level of the input D which is referenced at the low level. The flip-flop 123, by its input C, samples the input D, which is connected to the output Q ₁₂₂ , by the action of the falling edges of the signal E ₁ , the slot El.2 thus positions the output Q ₁₂₃ at the high level and the slot E1.α positions this output Q ₁₂₃ at the low level. The logical union in the NOR gate 124 with three inputs, supplemented by the inverter 125, of the three signals E1, Q ₁₂₂ and Q ₁₂₃ provides the output signal S1; the rising edges of the slots of this signal S1 provide the effective signals for synchronization of the automatic advance circuits.

The logic circuit 130 comprises the following components: an inverter 131, three flip-flops 132, 133 and 134 and a NOR gate 135 supplemented by an inverter 136. The operation of this logic circuit 130 will now be described with reference to FIG. 3c . The rising edge of the slots which constitute the signal SO applied to the input S of the flip-flop 132 positions the output Q ₁₃₂ at the high level, the falling edges of the signal E2.1 (E2 supplemented by the inverter 131) applied to the input C of the flip-flop sample the level of input D which is referenced at the low level. The rising edge of the slots of the signal SO which is also applied to the input S of the flip-flop 133 positions the output 0 ₁₃₃ of the latter at the high level; the falling edges of the signal E2.2. (signal E2 supplemented by the inverter 131) applied to the input C sample the level of the input D which is connected to the output Q 132 thus allowing the flip-flop 133 to be repositioned at the level low. The input D of the flip-flop 134 is sampled by its input C by the falling edges of the slots which constitute the signal E2, 2, the input D of the flip-flop 134 being connected to the output Q of the flip-flop 133; consequently, the output 0 of the flip-flop 134 is positioned at the high level by the falling edges of the slots E2.2 and at the low level by the falling edges of the slots E2.a and E2.1. The logical union in the NOR 135 gate, with three inputs, the output of which is complemented by the inverter 136, of the three signals E2, Q ₁₃₃ and Q ₁₃₄ provide the signal S2, the rising edges of this signal S2 provide the effective signals for synchronization of the automatic advance circuits.

The logic circuits which have just been described above can easily be produced from integrated logic components, such as NAND or NOR gates and D flip-flops, commercially available in standard boxes.

• - un corps métallique 140, creux, à l'intérieur duquel sont disposés les circuits électroniques, notamment, en protubérance, le circuit oscillant 141; ce corps 140 comporte: un moyen de fixation 142 dans l'épaisseur du carter du volant, ce moyen de fixation peut être constitué, par exemple, par une embase filetée, un moyen de serrage 143 constitué, par exemple, par une tête six pans,
• - des moyens de liaison électrique comprenant: un cordon bifilaire 144 terminé par une prise 145, comportant une sortie signal 145a et une entrée alimentation en énergie 145b; et une cosse rivetée 146 qui peut être reliée, si nécessaire, à la masse électrique du moteur.

FIG. 4 represents an embodiment of the detectors D1 and D2 of a sensor according to the invention; these two detectors are identical and of the proximity detector type using a high frequency oscillator whose oscillating circuit is damped by the proximity of a metallic object. A detector D includes:

• - A hollow metal body 140, inside which the electronic circuits are arranged, in particular, in protrusion, the oscillating circuit 141; this body 140 comprises: a fixing means 142 in the thickness of the flywheel housing, this fixing means can be constituted, for example, by a threaded base, a clamping means 143 constituted, for example, by a hexagonal head ,
• - electrical connection means comprising: a two-wire cord 144 terminated by a socket 145, comprising a signal output 145a and an energy supply input 145b; and a riveted terminal 146 which can be connected, if necessary, to the electrical ground of the motor.

The electronic circuits of the proximity detector, which are known per se, will not be described, since they are commercially available according to an integrated technology.

We will now describe an application of a sensor for measuring the position of the pistons to an electronic ignition system.

FIG. 5 represents, in the form of a functional diagram, a complete electronic ignition system for a four-cylinder combustion engine in which the electro-mechanical means 105a of a sensor according to the invention are integrated.

The engine 10 has four cylinders C1 to C4 shown in dotted lines. In the cylinders are arranged four spark plugs B1 to B4; the crankshaft 11 comprises four crank pins 12 which drive four connecting rods 13 connected to the four pistons P 1 to P4, the two pistons P and P4 constituting a first group of pistons and the pistons P2 and P3 constituting a second group of pistons; the engine ignition cycle is considered to correspond to the sequence 1, 3, 4, 2.

The crankshaft 11 drives a flywheel V on which is disposed a set of weights, formed of three weights, as shown in FIG. 2a.

On the steering wheel protection casing are arranged the detectors D1 and D2, already described in FIG. 4; the output signals from these detectors are applied to the inputs of the electronic means 105b of the sensor; these electronic means supply the synchronization signals SO, S1 and S2, as described above. Two spark generators 20a and 20b, with twin secondary, supply the spark plugs, the two outputs of the generator 20b being connected to the spark plugs B1 and B4 of the first group of pistons and the two outputs of the generator 20a being connected to the spark plugs B2 and B3 of the second group of pistons.

The distribution circuit 30 ensures, in a cyclic manner, the sequential triggering of the spark generators 20a and 20b; it has two inputs, a first input which receives the synchronization signal SO and a second input which receives the trigger pulses FO supplied by the automatic ignition advance circuits 40; this distribution circuit 30 has two outputs, corresponding to the two possible states, a first output providing trigger pulses F1 to the generator 20a and a second output providing trigger pulses F2 to the generator 20b.

The automatic ignition advance circuits 40 allow, on the one hand, below a determined speed of rotation NO of the engine, to directly transfer, at the output F0, the rising edges of the slots which constitute the signal S1 input and, on the other hand, beyond the NO rotation speed, to transfer with a delay, depending on the engine operating speed, to the output FO, the rising edges of the slots which constitute the signal input S2. The magnitude of the time delay introduced by the circuits 30 is controlled by an advance order signal V _m produced by a calculation circuit 50. This calculation circuit can be of a known type; it makes it possible to translate input measurement signals V1, V2 .... Vn, representative of the engine operating speed into a signal V _φ of order of advance / delay.

The configuration of the metal weights of an angular position sensor, according to the invention, must be adapted as a function of the number of groups of two cylinders that the engine comprises.

FIG. 6, for illustrative purposes, represents, in a schematic form, the electromechanical means 105a of an angular position sensor, according to the invention, intended to equip a six-cylinder engine comprising three groups of two cylinders, this sensor allowing synchronize an electronic ignition system comprising dual-channel automatic advance circuits, a three-state distribution circuit and three spark generators with twin secondary. The set of weights M, all identical, comprises the main weights Ml, M2 and M3 whose relative angular spacing is equal to 120 °; the auxiliary flyweight Mα is angularly offset by an angle φ _D equal to the relative spacing angle of the two detectors D1 and D2, the magnitude of this angle φ _D having a value at least equal to the maximum advance angle to order. The electronic means of the sensor are not shown in this FIG. 6 and remain identical to those described in FIG. 2a.

In general, it should be remembered that when the flyweights are driven in rotation directly on the engine crankshaft, it is always necessary to have spark generators with twin secondary. The configuration of the electromechanical means, adapted to an eight-cylinder engine is deduced directly from what has been described previously.

The configuration of the electromechanical means of an angular position sensor, according to the invention, must be modified when the weights are driven in rotation by. the engine timing shaft whose speed of revolution is equal to half that of the crankshaft.

FIG. 7, for illustrative purposes, represents, in a schematic form, the configuration of the electromechanical means 105a of an angular position sensor intended for a four-cylinder engine equipped with an ignition system comprising two generators of sparks with twin secondary. The set of weights is constituted by a first pair of main weights M 1 and M'1, diametrically opposite, and a second pair of identical main weights M2 and M'2, orthogonal to the first couple. The auxiliary weights Ma and M'α, identical to the previous main weights, are angularly offset, by an angle f whose value is equal to half of the angle φ _D shown in ia FIG. 2a, likewise the relative angular spacing of the two detectors D1 and D2 is also equal to the value φ ' _D. The electronic means 105b of the sensor as described previously in FIG. 2a remain identical. When the engine is equipped with four spark generators with a simple secondary (one of the secondary outputs being connected to ground), one of the additional flyweights Mα or M'α must be eliminated and a circuit of distribution of spark generator trigger signals, capable of taking four states. The configuration of the electromechanical means with a multi-cylinder engine is deduced directly from what has just been described above.

In the piston position sensor as described above, the auxiliary metal counterweight Ma is angularly offset late on the associated main counterweight M2; according to an alternative embodiment, this counterweight Ma can be angularly offset in advance on the associated main counterweight M2. In any electronic ignition system for an internal combustion engine, there is the problem of electromagnetic interference between the spark generators arranged at the outlet of the system and the piston position sensor which constitutes one of the input elements of this system; these electromagnetic interferences generate parasitic electrical signals at the instant of the rupture of the magnetic current passing through the primary windings of the very high voltage coils connected to the ignition plugs of the engine. For some models of internal combustion engines, the magnitude of the static advance angle can be positive and the minimum dynamic advance angle can be zero or even negative, corresponding to a delay in ignition of the engine as indicated , by way of illustrative example in FIG. 8 which represents, in the form of a curve, a typical advance law as a function of the speed of rotation of the motor.

In what follows, an embodiment of a position sensor will be described for which the auxiliary counterweight is angularly offset in advance on the associated main counterweight, this sensor further comprising means making it possible to inhibit the effect of parasitic signals induced by electromagnetic radiation from spark generators.

• - des moyens électromécaniques 105a comprenant, d'une part, un jeu de masselottes conductrices, disposé sur un disque entraîné en rotation synchrone par le vilebrequin du moteur, ce jeu de masselottes comportant des masselottes principales M1 et M2 diamétralement opposées et une masselotte auxiliare Ma disposée angulairement en avance d'une quantité 0, sur la masselotte associée M2, le sens de rotation du disque étant donné par la direction de la flèche et, d'autre part, un couple de détecteurs D1 et D2, disposé de façon ordonnée, en regard de la course des masselottes, l'espacement angulaire relatif φ_o des deux détecteurs étant égal sensiblement à l'angle φ₁; ces détecteurs D₁ et D₂ délivrent respectivement des signaux électriques E1 et E2 aux instants de passage des masseloftes,
• - des moyens électroniques de traitement 105b des signaux de sortie El et E2 des détecteurs D1 et D2, ces moyens électroniques comprenant, notamment, un circuit logique de coïncidence des signaux E1 et E2 qui fournit le signal de sortie SO permettant de synchroniser le distributeur électronique, et, des circuits permettant d'inhiber les signaux résultant du passage de la masselotte Ma devant les détecteurs D1 et D2.

FIG. 9 represents, in the form of a simplified diagram, an alternative embodiment of a position sensor according to the invention, this sensor making it possible to synchronize the ignition advance circuits and the electronic distributor of a electronic ignition system for a four-cylinder internal combustion engine, this sensor comprising:

• - electromechanical means 105a comprising, on the one hand, a set of conducting weights, disposed on a disc driven in synchronous rotation by the engine crankshaft, this set of weights comprising diametrically opposite main weights M1 and M2 and an auxiliary weight Ma angularly arranged in advance by a quantity 0, on the associated counterweight M2, the direction of rotation of the disc being given by the direction of the arrow and, on the other hand, a pair of detectors D1 and D2, arranged in an orderly fashion, opposite the travel of the weights, the relative angular spacing φ _o of the two detectors being substantially equal to the angle φ ₁ ; these detectors D ₁ and D ₂ respectively deliver electrical signals E1 and E2 at the instants of passage of the flyweights,
• electronic means 105b for processing the output signals E1 and E2 of the detectors D1 and D2, these electronic means comprising, in particular, a logic circuit for coincidence of the signals E1 and E2 which supplies the output signal SO making it possible to synchronize the electronic distributor , and, circuits making it possible to inhibit the signals resulting from the passage of the counterweight Ma in front of the detectors D1 and D2.

The relative angular spacing φ ₁ between the weights M2 and Mα may advantageously be greater than the angle φ _o .

FIG. 10 represents, referred to the TDC of the pistons, the timing diagrams of the main electrical signals associated with the sensor represented in FIG. 9. The signals E1 and E2 are identical, their relative angular offset being equal to the value φ _o , the square signals 1 'and 2' of the signal E1 are shifted in advance by the static angle of advance 8. The signal SO results from the temporal coincidence of the square signals 2 and a 'and the signals S2 and S1 consist of pulses which coincide with the rising edges of the square signals 1, 1 'and 2.2'.

• - une première porte logique 150 du type ET, cette porte logique recevant, sur une première entrée, le signal de sortie E2 du détecteur D2 et, sur une seconde entrée, le signal de sortie E1 du détecteur D1; elle fournit le signal SO permettant de synchroniser le distributeur électronique du système d'allumage,
• - une première bascule 151 du type "D" dans laquelle l'entrée de donnée (D) est polarisée au niveau haut, l'entrée d'horloge (C) reçoit le signal E2 et l'entrée de remise à zéro (R) est reliée à la sortie de la porte logique 150.
• - un circuit de détection des transitions du niveau du signal de sortie fourni par la sortie 0 de la bascule 151, ce circuit de détection comprenant une porte logique 152 du type "OU EXCLUSIF", les deux entrées de cette porte étant reliées à la sortie Q de la bascule 151, la première entrée en liaison directe, la seconde à travers une cellule de retard formée par la résistance R1 et la capacité C1; ce circuit de détection fournit le signal de sortie E2 en impulsions permettant de synchroniser les circuits d'avance automatique,
• - une seconde bascule 153 du type "D", dans laquelle l'entrée de donnée (D) est polarisée au niveau bas, l'entrée d'horlage (C) reçoit le signal E1 et l'entrée de mise au niveau haut (S) est reliée à la sortie de la porte logique 152.
• - une seconde porte logique 154 du type "ET", dans taquette une première entrée est reliée à la sortie Q de la bascule 153 et une seconde entrée reçoit le signal E1; cette porte logique fournit le signal en impulsions E1 permettant de déclencher les générateurs d'étincelles au point d'avance statique.

FIG. 11 represents, in the form of an electrical diagram, an embodiment of the electronic processing means 105b of the output signals E1 and E2 of the angular position sensor 105a shown in FIG. 9; these electronic means comprising:

• a first logic gate 150 of the AND type, this logic gate receiving, on a first input, the output signal E2 from the detector D2 and, on a second input, the output signal E1 from the detector D1; it supplies the signal SO making it possible to synchronize the electronic distributor of the ignition system,
• - a first flip-flop 151 of type "D" in which the data input (D) is polarized at the high level, the clock input (C) receives the signal E2 and the reset input (R) is connected to the output of logic gate 150.
• a circuit for detecting the transitions of the level of the output signal supplied by the output 0 of the flip-flop 151, this detection circuit comprising a logic gate 152 of the "EXCLUSIVE OR" type, the two inputs of this gate being connected to the output Q of flip-flop 151, the first direct link entry, the second at through a delay cell formed by the resistor R1 and the capacitor C1; this detection circuit supplies the output signal E2 in pulses making it possible to synchronize the automatic advance circuits,
• - a second flip-flop 153 of type "D", in which the data input (D) is polarized at the low level, the time-stamping input (C) receives the signal E1 and the input for leveling up ( S) is connected to the output of logic gate 152.
• - a second logic gate 154 of the "AND" type, in the plug a first input is connected to the output Q of the flip-flop 153 and a second input receives the signal E1; this logic gate supplies the signal in pulses E1 making it possible to trigger the spark generators at the point of static advance.

A description will now be given, with reference to the timing diagrams of the signals of FIG. 10, the operation of the electrical circuits represented in FIG. 11.

The square signal SO results from the temporal coincidence of the signals 2 and a 'from the sequence of the signals E2 and E1. The output Q of the flip-flop 151 is positioned at the high level by the rising edges of the signals 1 of the sequence of the signal E2 and positioned at the low level by the rising edges of the signal SO, the resulting square signal S3 has an angular duration of 180 degrees , this signal S3 is differentiated by the logic gate 152 to supply the signal S2 in synchronization pulses of the automatic advance circuits. The output Q of the flip-flop 153 is positioned at the high level by the signals S2 and positioned at the low level by the rising edges of the signal E1, to supply the signal S4, finally the conjunction operation performed by the logic gate 154 makes it possible to supply the signal S1. We therefore see, now, more clearly, the functions of these processing circuits, on the one hand, developing a signal for synchronizing the ignition cycle of the engine, on the other hand, eliminating the signals a and a 'resulting from the passage the flyweight Ma in front of detectors D1 and D2.

An electronic means will now be described making it possible to inhibit the spurious signals induced on the output of the detectors D1 and D2 by the electromagnetic radiation of the coils of the spark generators 20a and 20b. If we refer to FIG. 12 which partially represents the electronic ignition system described in FIG. 5, we see, on the one hand, that the signal SO supplied by the element 105b makes it possible to control the electronic distributor 30 and, on the other hand, that the output signal Fo, supplied by the automatic advance circuits 40 at ignition is sent to the processing circuits 105b in order to inhibit the signals E1 and E2 supplied respectively by the detectors D1 and D2 of the sensor 105a for a time corresponding to the duration of the parasitic signals resulting from the ignition sparks.

• - une bascule 155 du type "D", dans laquelle l'entrée de donnée (D) est polarisée, au niveau haut, l'entrée d'horloge (C) reçoit les signaux de sortie FO fournis par les circuits d'avance automatique 40, la sortie Q est reliée, par l'intermédiaire d'un réseau de retard, à l'entrée de remise à zéro (R) pour constituer une bascule monostable dont la durée est proportionnelle au produit de la valeur de la résistance R2 et de la valeur de la capacité C2,
• - une porte logique 156 du type "ET" dont une première entrée reçoit le signal E2 et une seconde entrée est reliée à la sortie Q de la bascule 155, la sortie de cette porte 156 est reliée à l'entrée d'horloge (C) de la bascule 151 déjà décrite.

FIG. 13 represents, in the form of an electrical diagram, an embodiment of the interference signal inhibition circuits; these circuits include:

• - a flip-flop 155 of the "D" type, in which the data input (D) is polarized, at the high level, the clock input (C) receives the output signals FO supplied by the automatic advance circuits 40, the output Q is connected, via a delay network, to the reset input (R) to constitute a monostable flip-flop whose duration is proportional to the product of the value of the resistance R2 and the value of the capacity C2,
• a logic gate 156 of the "AND" type, a first input of which receives the signal E2 and a second input is connected to the output Q of the flip-flop 155, the output of this gate 156 is connected to the clock input (C ) of the flip-flop 151 already described.

The logic gate 150 already described, has a third input connected to the output T of the flip-flop 155.

In practice, the duration of the inhibition signal supplied by the flip-flop 155 can be of the order of a millisecond, which corresponds substantially to the duration of the ignition sparks of the engine.

It will be noted that, in the case of a four-cylinder engine, the electronic distributor can be constituted by two logic gates of the "AND" type controlled directly by the signal S3.

We now see, more clearly, the advantages provided by an angular position sensor, according to the invention, in its applications to multi-cylinder internal combustion engines. On the one hand, the elements which constitute the electromechanical means of the sensor are robust and, consequently, perfectly adapted to the requirements of the industry of internal combustion engines and, on the other hand, the configuration of the electromechanical means can be suitable for different types of multi-cylinder engines; finally, the electrical signals supplied by the sensor are compatible with the various existing electronic ignition systems.

The invention is not limited, in its applications, to the synchronization of the circuits of an electronic ignition system; in particular, the output signals from the sensor can be used to provide, on the dashboard of a motor vehicle, the engine rotation speed information, or, these signals can be supplied to one or more angular speed discriminators to indicate the different engine rotation speeds.

The invention finds applications in the traction motor and stationary motor industry.

Claims (7)

1. A sensor (105a, 105b) for measuring the position of the pistons (P) of a multicyiinder (C) motor (10) equipped with an electronic ignition system (20, 30, 40), said sensor comprising a set of conducting members rotated synchronously by an output axis of the motor, two fixed detectors and an electronic means for processing the output signals of these detectors, characterized in that the sensor comprises an electromechanical means (105a) including a set of M + 1 identical conducting members of small dimensions, which are rotated by the crankshaft (11) of the motor, including further two fixed detectors (D1, D2) which deliver identical and mutually phase shifted electrical signals, and including an electronic means (105b) for processing the output signals of these two detectors, said electronic means including:

- a first logic coincidence circuit (110) combining the output signals of both detectors and delivering an output signal (So) corresponding to the ignition cycle of the motor,

-a second logic circuit (120, 130) connected to the output of both detectors and to the output of the first circuit (110) and furnishing respectively an output signal (S,) corresponding to the passage of the pistons near the Top Dead Center in the motor cylinders, and an output signal (S₂) corresponding to the passage of the pistons through a point ahead of the Top Dead Center in the motor cylinders, and that said set of M+ 1 conducting members comprises M regularly spaced main members (M₁,... M_i) and one (1) auxiliary member (Mα) which is angularly displaced with respect to one of the main members by an angle φ_D, said angle being at least equal to the maximum lead angle of motor ignition.

2. A sensor according to claim 1, characterized in that, the motor being of the type comprising an equal number of cylinders electrically associated in pairs, the set of M + 1 conducting members comprises a number of main members (M₁,... M_i) equal to the number of pairs of cylinders of the motor and a single auxiliary member (Ma) angularly displaced with respect to one of these main members.

3. A sensor according to claim 2, characterized in that, the rotation direction of the motor being determined, the auxiliary member (Ma) is angularly displaced in retard with respect to the corresponding main member.

4. A sensor according to claim 2, characterized in that, the rotation direction of the motor being determined, the auxiliary member is displaced in advance with respect to the corresponding main member.

5. A sensor according to claim 1, characterized in that, the set of M + 1 conducting members is mounted mechanically on the periphery of the inertia wheel of the motor and in face of the two detectors.

6. A sensor according to claim 5, characterized in that, the two detectors are mounted through the casing of this inertia wheel.

7. A sensor according to claim 6, characterized in that, the two detectors are of a type including an auto-oscillator which is dampened by the presence of a conducting member.

Images