FR2839361A1

FR2839361A1 - Method for regulating detector of magnetic variations, comprises use of electromagnetic winding with attenuated sinusoidal current to approach value which minimizes detector phase error

Info

Publication number: FR2839361A1
Application number: FR0205616A
Authority: FR
Inventors: Bennaceur Manssouri
Original assignee: Siemens VDO Automotive SAS
Current assignee: Continental Automotive France SAS
Priority date: 2002-05-06
Filing date: 2002-05-06
Publication date: 2003-11-07
Anticipated expiration: 2022-05-06
Also published as: FR2839361B1

Abstract

A rotating member (2) which has a tooth (3) and shoulders (3a,3b) turns adjacent to a magnet (4) and the resulting induction is measured by a Hall type sensor (5) which is connected (7) to a measuring unit (6). A phase error between the induction signal and the actual rotation of the member is corrected by applying to a compensating winding (9) an attenuated sinusoidal current which settles at a steady compensating value. Independent claims are also included for the following: (1) An electromagnetic winding which may be energized to modify the field of a detector permanent magnet and thus correct any phase error; (2) Application to position detector for internal combustion engine camshaft.

Description

rants. La presente invention est relative a un procede et un dispositif derants. The present invention relates to a method and a device for

reglage d'un detecteur du passage d'une discontinuite sur une piece metallique mobile, ce detecteur comprenant a) un aimant permanent definissant un entrefer avec la piece mobile, b) un capteur delivrant un signal representatif de ['induction regnant dans ledit entrefer, le passage de ladite discontinuite au niveau audit entrefer provoquant une variation de ladite induction et done le basculement audit signal entre des adjustment of a detector for the passage of a discontinuity on a movable metal part, this detector comprising a) a permanent magnet defining an air gap with the moving part, b) a sensor delivering a signal representative of the induction prevailing in said air gap, the passage of said discontinuity at said air gap causing a variation of said induction and therefore the switching to said signal between

premier et deuxieme niveaux.first and second levels.

On a represente a ia figure 1 du dessin annexe un mode de realisation d'un tel detecteur, repere 1, adapte a ia detection de la position angulaire d'une cible 2 tournant autour d'un axe X, comportant une "dent" 3 d'une ouverture angulaire de , cette dent 3 etant delimitee par des francs 3a et 3b. On monte couramment une telle cible sur l'arbre a cames dun moteur a combustion interne pour detecter le passage des francs 3a et 3b de la dent 3 devant le detecteur, pour les besoins du FIG. 1 of the accompanying drawing shows an embodiment of such a detector, marked 1, suitable for detecting the angular position of a target 2 rotating around an axis X, comprising a "tooth" 3 an angular opening of, this tooth 3 being delimited by francs 3a and 3b. Such a target is commonly mounted on the camshaft of an internal combustion engine to detect the passage of the francs 3a and 3b of tooth 3 in front of the detector, for the needs of the

controle du moteur, comme cela est bien connu. engine control, as is well known.

Le detecteur 1 comprend lui-meme un aimant permanent 4, pour etablir un champ d'induction magnetique dans lientrefer qui separe la cible 2 de l'aimant, et un capteur 5, a effet Hall par exemple, pour delivrer un signal representatif de l'intensite The detector 1 itself comprises a permanent magnet 4, to establish a magnetic induction field in the lientrefer which separates the target 2 from the magnet, and a sensor 5, for Hall effect for example, to deliver a signal representative of the 'intensity

de ce champ, a des moyens de mesure 6 de ce signal. of this field, has means 6 for measuring this signal.

L'aimant 4 et le capteur 5 ainsi que les conducteurs (non representes) qui relient le capteur 5 a la sortie 7 du detecteur 1, vent noyes dans un enrobage 8 qui The magnet 4 and the sensor 5 as well as the conductors (not shown) which connect the sensor 5 to the output 7 of the detector 1, are drowned in a coating 8 which

les solidarise et les protege.brings them together and protects them.

Le capteur 5 est dispose de maniere a etre sensible au champ diinduction etabli par l'aimant dans l'entrefer "magnetique" E, plus large que l'intervalle e qui separe physiquement la cible 2 du capteur 5, du fait que ce demier est. dans le mode de realisation represente a la figure 1, tangent a cet intervalle alors que The sensor 5 is arranged so as to be sensitive to the induction field established by the magnet in the "magnetic" air gap E, wider than the interval e which physically separates the target 2 from the sensor 5, because the latter is . in the embodiment represented in FIG. 1, tangent to this interval while

l'aimant 4 est dispose en retrait de l'intervalle, dans la masse de l'enrobage 8. the magnet 4 is set back from the gap, in the mass of the coating 8.

L'intensite du champ dans l'entrefer est etroitement liee a la largeur E de cet The intensity of the field in the air gap is closely related to the width E of this

entrefer, et done a la presence ou a ['absence de la dent 3 en face du capteur 5. air gap, and therefore to the presence or absence of the tooth 3 opposite the sensor 5.

C'est ainsi que le passage des discontinuites de la geometric de la cible 2, constituees par les francs 3a et 3b de la dent 3, provoquent des basculements du signal delivre par le capteur entre un niveau "haut" et un niveau "bas". il convient naturellement que ces basculements soient en phase avec les passages de ces Thus the passage of the discontinuities of the geometric of the target 2, constituted by the franks 3a and 3b of the tooth 3, cause the signal delivered by the sensor to switch between a "high" level and a "low" level. . it is natural that these changes are in phase with the passages of these

francs au droit du capteur 5.francs at the sensor 5.

Or on observe que le signal delivre par le capteur 5 est tres sensible a tout ecart de positionnement (dans les trots directions de l'espace) du detecteur par rapport a la cible, en particulier a tout ecart de la valeur de l'intervalle e, selon l'axe Z de l'aimant, par rapport a une valeur nominale. Un tel ecart a pour effet de dephaser les basculements du signal par rapport aux passages des francs 3a, 3b de la dent However, it is observed that the signal delivered by the sensor 5 is very sensitive to any deviation in positioning (in the three directions of space) of the detector relative to the target, in particular to any deviation from the value of the interval e , along the Z axis of the magnet, relative to a nominal value. Such a difference has the effect of shifting the tilting of the signal with respect to the passage of the francs 3a, 3b of the tooth

3au droit du capteur.3right to the sensor.

Une solution a ce probleme consiste a prevoir des moyens mecaniques de reg lage d u position nement du detecteur par rapport a la cible. La stabilite dans le temps du reglage ainsi obtenu niest cependant pas considere comme satisfaisante, tout comme ['integration d'un tel reglage dans la procedure de montage du capteur, One solution to this problem consists in providing mechanical means for adjusting the positioning of the detector relative to the target. The stability over time of the adjustment thus obtained is however not considered to be satisfactory, as is the integration of such adjustment in the sensor mounting procedure,

qui conduit a une trop grande dispersion de ce reglage, de detecteur a detecteur. which leads to too great a dispersion of this adjustment, from detector to detector.

On a aussi propose d'agir sur le champ regnant dans l'entrefer, non plus par un reglage de l'intervalle e ou E mais par une rectification mecanique de la It has also been proposed to act on the prevailing field in the air gap, no longer by adjusting the interval e or E but by a mechanical correction of the

geometric de l'aimant, propre a modifier l'intensite du champ regnant dans l'entrefer. geometric of the magnet, suitable for modifying the intensity of the prevailing field in the air gap.

On a egalement propose de proceder a cette rectification a ['aide d'un faisceau de rayonnement laser. Dans l'un ou l'autre cas, il faut que l'aimant soit accessible, done non enrobe ou non monte dans sa position finale, ce qui induit des imprecisions supplementaires une fois le montage final realise. Par ailleurs, il y a alors production de particules arrachees a l'aimant, et done de poussieres salissantes. Enfin le procede etant destructif, il n'est pas possible de revenir en arriere si la quantite de It has also been proposed to carry out this rectification using a beam of laser radiation. In either case, the magnet must be accessible, therefore uncoated or unmounted in its final position, which induces additional inaccuracies once the final assembly has been carried out. Furthermore, there is then production of particles torn from the magnet, and therefore of dirty dust. Finally, the process being destructive, it is not possible to go back if the quantity of

matiere aimantee arrachee pendant le reglage est excessive. magnetic material torn off during adjustment is excessive.

La presente invention a done pour but de fournir un procede de reglage d'un d etecteur d u passage d' une di scontin uite d' u ne piece metal l iq u e mob i le, qui n e presente pas les inconvenients des procedes de la technique anterieure decrits ci dessus et qui, en particulier, autorise un reglage en fin de ligne d'assemblage du capteur, n'implique aucune operation irreversible et se prete a une automatisation poussee. On atteint ce but de ['invention, ainsi que d'autres qui apparatront a la lecture The object of the present invention is therefore to provide a method for adjusting a detector for the passage of a di scontin uite of a metal part which is mobile, which does not present the drawbacks of the processes of the technique. described above and which, in particular, allows adjustment at the end of the assembly line of the sensor, does not involve any irreversible operation and is suitable for advanced automation. This object of the invention is achieved, as well as others which will appear on reading.

de la description qui va suivre, avec un procede de reglage d'un detecteur du of the description which follows, with a method of adjusting a detector of the

passage d'une discontinuite sur une piece metailique mobile du type decrit en passage of a discontinuity on a mobile metal part of the type described in

preambule de la presente description, ce procede etant remarquable en ce qu'on preamble to the present description, this process being remarkable in that

regle a une valeur predeterminee le decalage temporel observe entre ledit passage de ladite discontinuite et le basculement d'un signal representatif de ['induction regnant dans l'entrefer defini entre l'aimant permanent et la piece mobile, en set to a predetermined value the time difference observed between said passage of said discontinuity and the tilting of a signal representative of the induction prevailing in the air gap defined between the permanent magnet and the moving part, in

ajustant localement l'aimantation de itaimant. locally adjusting the magnetization of the magnet.

Comme on le verra plus loin en detail, un tel ajustement local de l'aimantation de l'aimant permanent du detecteur permet d'atteindre les buts annonces ci-dessus, d u fait q ue le reg lage de l'aimantati on est reversible, n on destructif, prop re a etre execute sur un detecteur completement assemble, le procede etant en outre As will be seen below in detail, such a local adjustment of the magnetization of the permanent magnet of the detector makes it possible to achieve the aims announced above, since the adjustment of the magnetization is reversible, n destructive, suitable for being executed on a fully assembled detector, the process being furthermore

fortement automatisable, done de cout contenu. highly automatable, therefore costly.

Suivant d'autres caracteristiques, optionnelles, de la presente invention: - ledit decalage temporel est regle a une valeur nulle, - on rapproche progressivement, par pas, ladite aimantation du niveau correspondent a ladite valeur predeterminee, - ledit rapprochement s'opere d'abord par un reglage grossier desdits pas, puis par un reglage fin, a l'approche du niveau correspondent a ladite valeur predeterminee, - lors d'un pas de reglage de ladite aimantation, on applique localement audit aimant le champ d'une bobine electromagnetique alimentee par un According to other optional features of the present invention: - said time offset is set to zero, - we progressively approximate, in steps, said magnetization of the level correspond to said predetermined value, - said approximation operates from first by a rough adjustment of said steps, then by a fine adjustment, when approaching the level corresponding to said predetermined value, - during an adjustment step of said magnetization, the field of an electromagnetic coil is locally applied to said magnet powered by a

courant evoluant en sinusode amortie. current evolving in damped sine wave.

D'autres caracteristiques et avantages de la presente invention appara'^tront Other characteristics and advantages of the present invention will appear.

a la lecture de la description qui va suivre et a l'examen du dessin annexe dans on reading the description which follows and examining the accompanying drawing in

lequel: - la figure 1 est un schema d'un dispositif pour la mise en oeuvre du procede suivant ['invention, applique a un detecteur decrit en preambule which: - Figure 1 is a diagram of a device for implementing the method according to [the invention, applied to a detector described in the preamble

de la presente description, etof this description, and

- les figures 2 et 3 vent des graphes utiles a la description de ce procede. - Figures 2 and 3 are graphs useful for the description of this process.

On se refere aux graphes de la figure 2 ou l'on a represente en A, les variations de l'intervalle e iors de la rotation de la cible 2 et, en B. les variations correspondantes du niveau N du signal delivre par le capteur 5 aux moyens 6 de mesure de ce signal. II s'agit la de variations temporelles mesurees, comme cela est courant en electronique automobile, par les angles de rotation a correspondents de We refer to the graphs of FIG. 2 where we have represented in A the variations in the interval during the rotation of the target 2 and in B. the corresponding variations in the level N of the signal delivered by the sensor 5 to the means 6 for measuring this signal. These are temporal variations measured, as is common in automotive electronics, by the corresponding angles of rotation of

la cible 2.target 2.

C'est ainsi que, la cible 2 etant supposee tourner a vitesse constante, I'intervalle e (signal A) prend l'une ou l'autre de deux valeurs distinctes, presentes chacune pendant un demi-tour de la cible, soit 180 , le passage des francs 3a, 3b de Thus, since the target 2 is supposed to rotate at constant speed, the interval e (signal A) takes one or the other of two distinct values, each present during a half-turn of the target, i.e. 180 , the passage of francs 3a, 3b of

Ia dent 3 au droit du capteur 5 definissant les transitions entre ces deux valeurs. Ia tooth 3 to the right of the sensor 5 defining the transitions between these two values.

Comme on l'a indique plus haut, on observe cependant que les basculements du signal B delivre par le capteur 5, qui devraient idealement etre parfaitement synchrones avec les passages des francs de la dent 3 au droit du capteur 5, peuvent etre dephases, symetriquement, par rapport a ceux-ci. Comme on l'a vu plus haut, ces dephasages vent attribuables a des ecarts, par rapport a des valeurs nominales, de la valeur de l'intervalle _, ou de l'intensite d'aimantation de As indicated above, it is observed however that the rockings of the signal B delivered by the sensor 5, which should ideally be perfectly synchronized with the passages of the francs of the tooth 3 to the right of the sensor 5, can be phase-shifted, symmetrically , compared to these. As we saw above, these phase shifts are attributable to deviations, compared to nominal values, of the value of the interval _, or of the intensity of magnetization of

l'aimant 4, en particulier.magnet 4, in particular.

C'est ainsi que i'impulsion du signal B qui correspond au passage de la dent 3 peut prendre soit une "largeur" B. inferieure a 180 , soit une largeur B2 superieure a 180 . Les fronts de montee et de descente, de l'impulsion B par exempie, vent dephases de + p et -<p respectivement, par rapport aux fronts correspondents du signal A. Suivant la presente invention, on annule, ou du moins on minimise ce dephasage, pour un entrefer de valeur predeterminee, en ajustant iocalement l'intensite d'aimantation de l'aimant 4, a i'aide d'une bobine electromagnetique de demagnetisation 9, ou de magnetisation comme on le verra plus loin, montee coaxialement sur le detecteur 1, par rapport a l'axe Z de ce dernier, a une distance d Thus the pulse of signal B which corresponds to the passage of tooth 3 can take either a "width" B. less than 180, or a width B2 greater than 180. The rising and falling edges, of pulse B for example, wind dephases of + p and - <p respectively, relative to the corresponding edges of signal A. According to the present invention, this is canceled, or at least minimized. phase shift, for an air gap of predetermined value, by adjusting the magnetization intensity of magnet 4 iocally, using an electromagnetic coil of demagnetization 9, or magnetization as will be seen below, mounted coaxially on detector 1, with respect to the latter's Z axis, at a distance d

de i'extremite adjacente de cet aimant, comme represente a la figure 1. from the adjacent end of this magnet, as shown in Figure 1.

Bien que ce dernier puisse prendre diverges formes, cylindrique, parallelepipedique, etc... courantes, une forme preferee selon la presente invention est celle d'un aimant "a cavite", cylindrique par exemple, ou, par assimilation, en U. Although the latter can take various forms, cylindrical, parallelepipedal, etc ... common, a preferred shape according to the present invention is that of a magnet "cavity", cylindrical for example, or, by assimilation, in U.

comme represente a la figure 1.as shown in figure 1.

Un tel aimant etablit en effet un champ dans i'entrefer dont la composante "statique" est relativement faible, ce qui permet d'utiliser dans le detecteur 1 un capteur 5 a effet Hall peu couteux et peu sensible a des variations de la temperature Such a magnet indeed establishes a field in the air gap whose "static" component is relatively small, which allows the use in detector 1 of an inexpensive Hall effect sensor 5 which is not very sensitive to variations in temperature.

de travail du capteur 5.sensor 5.

On comprend qu'en alimentant la bobine 9 avec des moyens (non representes) tels qu'une source de tension propre a faire passer un courant I dans la bobine, on va etablir autour de la bobine un champ magnetique qui, suivant le sens du courant', sera propre a demagnetiser ou a magnetiser, I'aimant 4 adjacent. Le degre de la desaimantation ou de l'aimantation obten u peut etre aj u ste par l' i nten site It is understood that by supplying the coil 9 with means (not shown) such as a voltage source suitable for passing a current I through the coil, we will establish around the coil a magnetic field which, according to the direction of the current ', will be suitable for demagnetizing or magnetizing, the magnet 4 adjacent. The degree of demagnetization or magnetization obtained u can be adjusted by the internal site

du courant fourni et par le reglage de la distance d. of the current supplied and by adjusting the distance d.

L'intensite du courant et/ou la distance _ vent ainsi regiees en fonction du dephasage p, qui peut etre facilement mesure a ['aide des moyens de mesure du The intensity of the current and / or the distance _ wind thus regulated as a function of the phase shift p, which can be easily measured using the means of measuring the

signal delivre par le capteur 5.signal delivered by the sensor 5.

En ce qui concerne l'intensite du courant on prefere, suivant ['invention, faire evoluer celui-ci dans le temps comme illustre a la figure 3, en sinusode amortie, jusqu'a un niveau diintensite i0. Celui-ci correspond au champ a etablir pour amener l'aimantation de l'aimant 4 (et done le champ dans 1'entrefer) au niveau requis pour annuler le dephase rp mesure par les moyens 6, ou du moins pour minimiser ce dephasage. L'alimentation de la bobine avec un courant evoluant rapidement en sinusode amortie, avec 4 ou 5 maxima par exemple, assure la tenue dans le temps du reglage ou "caiibrage" obtenu, I'aimantation de l'aimant suivant le meme profil As regards the intensity of the current, it is preferred, according to the invention, to evolve it over time as illustrated in FIG. 3, in damped sine wave, up to a diintensity level i0. This corresponds to the field to be established to bring the magnetization of the magnet 4 (and therefore the field in the air gap) to the level required to cancel the phase rp measured by means 6, or at least to minimize this phase shift. The supply of the coil with a rapidly evolving current in damped sine wave, with 4 or 5 maximum for example, ensures the resistance over time of the adjustment or "caiibrage" obtained, the magnetization of the magnet according to the same profile

pour prevenir une derive ulterieure de cette aimantation. to prevent a further drift of this magnetization.

Suivant ['invention, on prefere proceder au reglage decrit ci-dessus en partant d'un etat du detecteur qui implique que ce reglage s'opere par demagnetisation de l'aimant, plutot que par magnetisation de ce demier pour According to the invention, it is preferable to carry out the adjustment described above, starting from a state of the detector which implies that this adjustment is effected by demagnetization of the magnet, rather than by magnetization of the latter for

assurer une plus grande stabilite de la magnetisation finale de l'aimant. ensure greater stability of the final magnetization of the magnet.

On remarquera cependant que le procede suivant ['invention est parfaitement reversible et non destructif. C'est ainsi que si une phase de demagnetisation s'avere avoir depasse son objectif, il sera possible de remagnetiser i'aimant a un niveau superieur propre a atteindre ltobjectif d'annulation ou de minimisation du dephasage recherche. On notera a cet egard que l'on pourrait tout aussi bien regler ce dephasage a une vaieur constante, facile a prendre en compte pour retrouver 1a position vraie de Note, however, that the process according to the invention is perfectly reversible and non-destructive. Thus, if a demagnetization phase turns out to have exceeded its objective, it will be possible to re-magnetize the magnet to a higher level capable of achieving the objective of canceling or minimizing the phase shift sought. It will be noted in this regard that we could just as easily adjust this phase shift to a constant value, easy to take into account to find the true position of

la cible.target.

La demagnetisation, ou la magnetisation, de l'aimant pour l'amener au niveau d'aimantation optimai recherche s'opere preferablement, suivant la presente invention, par pas successifs propres a amener progressivement ie dephasage initial rp constate a une valeur optimale p0, constante, minimale ou nulle comme on 1'a vu plus haut. Avantageusement on procede d'abord par un reglage grossier, puis par The demagnetization, or magnetization, of the magnet to bring it to the optimum level of magnetization sought is preferably carried out, according to the present invention, by successive steps suitable for bringing gradually the initial phase shift rp found at an optimal value p0, constant, minimal or zero as we saw above. Advantageously, one proceeds first by a coarse adjustment, then by

un reglage fin, a l'approche du niveau d'aimantation optimal recherche. fine adjustment, approaching the optimal level of magnetization sought.

11 apparat maintenant que 1'invention permet bien d'atteindre les buts annonces, a savoir fournir un procede de reglage d'un detecteur du type decrit ci dessus, pouvant etre mis en ceuvre en fin de ligne d'assemblage de ces detecteurs, se pretant a une automatisation poussee et n'impliquant aucune operation It now appears that the invention does indeed achieve the stated aims, namely to provide a method of adjusting a detector of the type described above, which can be implemented at the end of the assembly line of these detectors, pretending to a high level of automation and involving no operation

irreversible sur le detecteur.irreversible on the detector.

Bien entendu ['invention n'est pas limitee au reglage d'un detecteur de position angulaire d'un arbre a Games d'un moteur a combustion interns, comportant une cible dentee et un capteur a effet Hall. Wile s'etend, au contraire, a tout detecteur electromagnetique de position, angulaire ou lineaire, a entrefer, et done a reluctance, variable. Of course, the invention is not limited to the adjustment of an angular position detector of a games shaft of an internal combustion engine, comprising a toothed target and a Hall effect sensor. Wile extends, on the contrary, to any electromagnetic position detector, angular or linear, with air gap, and therefore with reluctance, variable.

Claims

1. Method for adjusting a detector (1) for the passage of a discontinuity (3a, 3b) of a movable metal part (2), said detector (1) comprising a) a permanent magnet (4) defining an air gap (E) with said moving part (2), b) a sensor () delivering a signal (B) representative of the induction prevailing in said air gap (E), the passage of said discontinuity (3a, 3b) at said air gap (E) causing a variation of said induction and therefore the switching to said signal (B) between first and second levels, process characterized in that the time offset (<p) observed between said passage of said is adjusted to a predetermined value discontinuity (3a, 3b) and said tilting to said signal (B), by locally adjusting the magnetization to said magnet (4)

2. Method according to claim 1, characterized in that said

offset is set to zero.

3. Method according to any one of claims 1 and 2,

characterized in that the magnetization is gradually brought closer by step

level correspond to said predetermined value.

4. Method according to claim 3, characterized in that said approximation takes place first by a rough adjustment of said steps, then by a

fine adjustment, at the approach of a level correspond to said predetermined value.

5. Method according to any one of claims 3 and 4,

characterized in that, during a setting step of said magnetization, the field of an electromagnetic coil (9) supplied is locally applied to said magnet (4)

by a current evolving in damped sine wave.

6. Method according to any one of claims 1 to 5,

characterized in that it sets the time offset led (<p) by local demagnetization

audit magnet (4).

7. Device for implementing the method according to one

any one of claims 1 to 6, characterized in that it comprises a) a

electromagnetic coil (9) mounted in a predetermined relative position around said detector (1), and b) means for supplying said coil with a current (i) suitable for locally altering the magnetization of the permanent magnet (4) to said detector (1), so as to adjust said time offset (<p) to a predetermined value.

8. AppUcaBon of the disposal conforms to vendlcaBon 7, to the adjustment

a dA1eur (1) of the angular position of a 10urnan1 arbm.

9. AppUcaBon conforms la récendicaBon 8, camp en qua leak