EP0768695A1 - Contactor for starter with improved fixed contacts, and starter for motor vehicle equipped with such a contactor - Google Patents

Abstract

The switch for the starter of the vehicle comprises a mobile contact element (26) made of electrically conducting material, movable between a rest position and an active position in which it establishes connection between two fixed contacts (42). Movement of the mobile contact is achieved by use of a magnetic core moving axially with an electromagnetic core. At least one and preferably both of the main fixed contacts (42) is electrically connected to an auxiliary fixed contact (52). The free end of each auxiliary contact is placed such that the mobile contact element comes into contact with the auxiliary contacts as it moves towards the closed position. The auxiliary contacts are made of a conductive material with non-zero resistance, so that current flow starts to occur before connection of the main contacts.

Description

The present invention relates to a starter switch for a motor vehicle.

According to a known design, the contactor comprises a movable contact element, made of an electrically conductive material, the movements of which are controlled from a rest position towards an active position in which it electrically connects the heads of two fixed contact terminals.

The movable contact element is resiliently returned to its rest position and its movements along its actuating stroke with a view to establishing power contact between the two main terminals of the contactor, are controlled by a movable core mounted sliding inside a set of contactor windings.

The movable contact element is for example made in the form of a contact plate which is arranged in a plane substantially perpendicular to its direction of movement and the front face of which faces the heads of the fixed contact terminals electrically connects these two heads when it reaches its active position.

The establishment of contact between the contact plate and the contact terminal heads is therefore in the form of a non-slip impact.

The impact of closing the electrical circuit by the movable contact plate generally creates contact bounces.

These rebound phenomena cause reopening of one of the two contacts, each of which consists of a head of a contact terminal and the movable contact plate, and this results in electric arcs which can cause a phenomenon of sticking of the plate against the contact heads by fusion of copper particles.

In the event of sticking, it becomes impossible to stop the starter fitted with the contactor, which very quickly leads to its destruction.

The reopening of the contacts due to the closing impact also causes accelerated wear of the heads of the contact terminals.

When the electrical circuit is established by the contacting of the movable contact plate, the abrupt and immediate establishment of the full supply voltage of the starter motor is harmful to the life of the brushes of this motor.

In the event of icing of one of the contact parts, in particular of the heads of the contact terminals, the starter cannot operate.

Only the force of the contact closure impact can cause the frost deposited on the elements to break, causing it to burst.

However, it is noted that the value of the impact forces is insufficient, in the majority of icing cases, to burst the frost and allow an electrical contact to be established.

The present invention aims to propose a new design of a starter switch of the type mentioned above which overcomes these drawbacks.

To this end, the invention provides a contactor characterized in that at least one fixed contact terminal is electrically connected to an auxiliary fixed contact with which the movable contact element comes to cooperate, for its electrical connection with the associated fixed terminal , in an intermediate position between its rest position and its active position.

• le contact fixe auxiliaire s'étend sensiblement parallèlement à la direction de déplacement de l'élément mobile de contact, et l'élément mobile de contact coopère avec le contact fixe auxiliaire le long de sa course de déplacement entre ladite position intermédiaire et sa position active ;
• le contact fixe auxiliaire possède une résistance électrique propre non nulle qui détermine une valeur réduite de l'intensité du courant électrique qui traverse le circuit électrique qui relie les deux bornes fixes de contact lorsque l'élément mobile de contact coopère avec le contact fixe auxiliaire ;
• l'élément mobile de contact est susceptible de coopérer avec le contact fixe auxiliaire par un bord latéral, et avec la tête de la borne fixe de contact associée par une portion de surface transversale sensiblement perpendiculaire à la direction de ses déplacements et qui est délimitée par ledit bord latéral ;
• le contact fixe auxiliaire est réalisé sous la forme d'une lame conductrice déformable élastiquement qui est déformée par l'élément mobile de contact lorsque celui-ci coopère avec la lame conductrice, pour garantir l'établissement d'un bon contact électrique entre ces deux éléments ;
• la lame conductrice est réalisée venue de matière avec une cosse annulaire traversée par le corps de la borne fixe et qui est en appui axial contre la face annulaire de raccordement entre la tête et le corps de la borne fixe ;
• chacune des deux bornes fixes de contact est reliée à un contact fixe auxiliaire associé ;
• les têtes des deux bornes fixes de contact sont agencées dans un même plan perpendiculaire à la direction de déplacement de l'élément mobile de contact qui est réalisé sous la forme d'une plaque de contact qui s'étend dans un plan sensiblement perpendiculaire à la direction de ses déplacements ;
• les deux contacts fixes auxiliaires s'étendent sur la même longueur.

According to other characteristics of the invention:

• the auxiliary fixed contact extends substantially parallel to the direction of movement of the movable contact element, and the movable contact element cooperates with the auxiliary fixed contact along its displacement travel between said intermediate position and its active position ;
• the auxiliary fixed contact has a non-zero own electrical resistance which determines a reduced value of the intensity of the electric current which crosses the electric circuit which connects the two fixed contact terminals when the movable contact element cooperates with the auxiliary fixed contact;
• the movable contact element is capable of cooperating with the auxiliary fixed contact by a lateral edge, and with the head of the fixed contact terminal associated by a portion of transverse surface substantially perpendicular to the direction of its movements and which is delimited by said side edge;
• the auxiliary fixed contact is produced in the form of an elastically deformable conductive strip which is deformed by the movable contact element when the latter cooperates with the conductive strip, to guarantee the establishment of a good electrical contact between these two elements;
• the conductive strip is produced integrally with an annular terminal through which the body of the fixed terminal passes and which is in axial abutment against the annular connection face between the head and the body of the fixed terminal;
• each of the two fixed contact terminals is connected to an associated auxiliary fixed contact;
• the heads of the two fixed contact terminals are arranged in the same plane perpendicular to the direction of movement of the movable contact element which is produced in the form of a contact plate which extends in a plane substantially perpendicular to the direction of its movements;
• the two auxiliary fixed contacts extend over the same length.

The invention also provides a starter for a combustion engine of a motor vehicle, characterized in that it is equipped with a contactor produced in accordance with the teachings of the invention.

• la figure 1 est une vue en section axiale partielle d'un contacteur de démarreur réalisé conformément aux enseignements de l'invention ;
• la figure 2 est un schéma électrique permettant d'illustrer l'établissement du raccordement électrique du contact de puissance d'un démarreur équipé d'un contacteur selon l'invention et qui est illustré dans la position de repos de l'élément mobile de contact ;
• la figure 4 est une vue similaire à celle de la figure 3 sur laquelle l'élément mobile de contact est illustré dans une position intermédiaire ;
• la figure 5 est une vue similaire à celle des figures 3 et 4 dans laquelle l'élément mobile de contact est illustré dans sa position active ; et
• la figure 6 est une vue similaire à celle des figures 3 à 5 dans laquelle l'élément mobile de contact est illustré dans une position anormale correspondant à un défaut d'établissement du contact.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

• Figure 1 is a partial axial sectional view of a starter switch made in accordance with the teachings of the invention;
• FIG. 2 is an electrical diagram making it possible to illustrate the establishment of the electrical connection of the power contact of a starter equipped with a contactor according to the invention and which is illustrated in the rest position of the movable contact element ;
• Figure 4 is a view similar to that of Figure 3 in which the movable contact element is illustrated in an intermediate position;
• Figure 5 is a view similar to that of Figures 3 and 4 in which the movable contact element is illustrated in its active position; and
• Figure 6 is a view similar to that of Figures 3 to 5 in which the movable contact element is illustrated in an abnormal position corresponding to a failure to establish contact.

FIG. 1 shows a contactor 10 intended to equip a motor vehicle starter (not shown) and which consists essentially of a magnetic carcass 12 which receives a fixed set of windings 14 and a fixed pole core 16.

The electrical supply of the windings 14 is capable of causing the displacement, from right to left when considering FIG. 1, of a movable core 18 which is resiliently returned by a spring 20 to its rest position illustrated in FIG. 1 and which is capable of sliding with a control rod 22 slidingly mounted in the core 16 and whose free end 24 situated at the front of the fixed pole core 16 carries a movable contact element 26.

The movable contact element is produced in the form of a movable contact plate of generally rectangular shape, the rear face 28 of which is resiliently returned to its rest position illustrated in FIG. 1 in which it bears axially against the face front 30 of the fixed polar core 16.

The movable contact plate 26 is returned to this position by a return spring 32 which is interposed between the front end 24 of the control rod 22 and the transverse bottom 34 of a cover 36 for closing the contactor which is mounted crimped at the front end 38 of the carcass 12.

According to a known design, and under the action of the mobile core 18, the mobile contact plate 26 is capable of electrically connecting the contact heads 40 of two terminals 42 which are terminals fixed in the transverse bottom 34 of the cover 36.

The contact heads 40 are located inside the cover and bear against the internal face of the transverse bottom 34, each by its annular face 44 which delimits the head 40 relative to the body 46 of the contact terminal 42 which passes through the transverse bottom 34 to allow the connection of the terminals to the supply circuit of the starter motor, as will be explained below with reference to FIGS. 2 to 6 .

The rear faces 48 of the two contact heads 40 are situated substantially in the same plane perpendicular to the axis XX of the contactor, that is to say perpendicular to the direction of movement of the movable contact plate 26 which is capable of electrically connect the two terminals 42 when its front face 50 which comes into contact with the faces 48 of the heads 40 of the terminals 42.

Each of the terminals 42, like the movable contact plate 26, is made of electrically conductive material and it is mounted in the cover of insulating material 36.

In accordance with the teachings of the invention, each of the heads 40 of a terminal 42 is associated with an auxiliary fixed contact 52 which is illustrated in detail in FIG. 2.

Each auxiliary contact 52 is a part produced by cutting and folding in a sheet of conductive material.

Each auxiliary contact 52 comprises an annular terminal 54 which is interposed between the annular face 44 of the associated contact terminal 42 and the internal face of the bottom 34 of the closure cover 36 which comprises a groove of complementary shape for the positioning of the terminal 54 .

The terminal 54 is extended by a conductive strip 56 which extends longitudinally, that is to say in a direction parallel to the axis XX of the contactor, along the contact head 40 and beyond the face front 48 of head 40.

The blade 56 is elastically deformable and it has at its rear free end 58 a portion 60 folded down substantially at 180 ° which constitutes a ramp for cooperate with the corresponding lateral edge 62 of the movable contact plate 26.

The ramp 60 thus extends opposite the edge 62.

When the movable contact plate 26 moves from its rest position illustrated in FIG. 1 to its active position in which its front face 50 will be in contact with the rear faces 48 of the heads 40 of the contact terminals 42, it comes from firstly cooperate by its lateral edge 62 with the auxiliary contacts 52 in an intermediate position and therefore before the contact is established by its front face 50.

Each terminal 50 may include means (not shown) for its angular indexing relative to the cover 36 so that it occupies its mounting position illustrated in FIG. 1 in which its beak 60 extends opposite the lateral edge 62.

In the electrical diagram illustrated in FIG. 3, a starter 64 is shown comprising an electric motor 66, one terminal 68 of which is connected to the electrical ground 70 and the other terminal 72 of which is connected to one of the terminals 42 of the contact. of contactor power.

The other fixed terminal 42 is connected to the positive pole + BAT of the vehicle's storage battery.

The electrical diagram in FIG. 3 also shows the switch 74 for supplying the winding assembly 14 of the contactor 10 which connects the positive pole + BAT to a midpoint 76 of the winding assembly 14, including the coil call 15 is connected to the electrical ground 70 and the other coil 13 of which is connected to the fixed terminal 42 to which the motor 72 is connected.

The two auxiliary contacts 52 and the movable contact 26 have also been shown.

In accordance with a characteristic of the invention, each auxiliary fixed contact 52 has a specific non-zero electrical resistance which is shown diagrammatically by a resistance R in FIGS. 3 to 6.

When the driver of the vehicle equipped with the starter 64 causes the closing of the switch 74, he feeds the set of coils 14 which causes a displacement of the movable core 18 which leaves its rest position illustrated in FIGS. 1 and 3 to simultaneously move the movable contact 26, which leaves its rest position.

During this actuating stroke, the movable contact 26 as illustrated in FIG. 4, reaches an intermediate position in which it is in contact simultaneously with the two fixed auxiliary contacts 52.

The electric motor 66 is then supplied by the vehicle battery through the two resistors R of the auxiliary fixed contacts 52 which are in series in the electric circuit connecting the positive pole + BAT of the battery to the motor 66.

The voltage at terminals 68 and 72 of the motor 66 is thus reduced, and it is a current of reduced intensity l1 which flows in its supply circuit comprising the two resistors R in series.

The value of resistors R is high enough not to cause rotation of the starter armature.

Under the action of the movable core 18, the actuating stroke of the movable contact 26 continues from the intermediate position illustrated in FIG. 4, until it reaches the active position illustrated in FIG. 5 in which the contact mobile 26 establishes the supply of the motor 66 directly, the supply circuit then connecting the positive pole + BAT of the battery to the terminal 72 of the motor directly to through the movable contact plate 26 which is in contact with the heads 40 of the fixed terminals of the contactor.

It is then a current l2 of maximum intensity which flows through the motor supply circuit, this value always being less than the value that the starter would have absorbed if there had not been a prior phase of rotation at reduced speed. (in the intermediate position illustrated in Figure 4) due to the existence of a counter-electromotive force during this first phase.

Sudden peaks of high current were thus avoided by reducing the phenomenon of premature wear of the brushes of the motor 66.

FIG. 6 shows an abnormal operation of the contactor.

This malfunction can have two causes.

A first cause results for example in the icing of a contact.

The terminal 40 connected to the + BAT pole of the battery can be isolated by a layer of frost which prevents the movable contact plate 26 from coming into contact with this terminal 40 at the end of the actuation stroke.

The current l3 which then supplies the motor 66 is lower than the normal current of maximum intensity l2 because one of the resistors R is then inserted in series in the supply circuit in the terminal 72 of the motor 66.

The associated auxiliary fixed contact 52 then heats up by the Joule effect.

By thermal conduction, the terminal 42 with its head 40 heats up to cause the melting of the frost which covered it, which, after a certain time, makes it possible to restore normal contact of the two movable contacts 26 with the head 40 of the type of that illustrated in FIG. 5.

In the case where the heads 40 are iced, the principle of defrosting by heating the fixed auxiliary contact 52 is identical, each of the two auxiliary contacts being traversed by a current of reduced intensity l1.

Another cause of the malfunction shown in Figure 6 can be contact bounce.

Due to the design of the fixed auxiliary contacts 52, the rebounds caused by mechanical oscillations have a much lower probability of appearance than in the case of traditional contacts comprising only the heads 40 of the fixed terminals 42.

In fact, during the approach phase of the movable contact 26, the speed of the latter is slowed down due to the friction 60 of the auxiliary fixed contacts 52 with the lateral edge 62 of the contact plate 26 and, on the other hand, the oscillatory energy is absorbed in part by friction along these same auxiliary contacts 52.

However, in the event that a reopening remains due to a rebound phenomenon, the movable contact 26 occupies the position illustrated in FIG. 6, or in FIG. 3, the supply current of the motor 66 however not being interrupted .

There is therefore no appearance of an electric arc and the supply current is only reduced during the period of oscillation of the movable contact 26.

The design of the contactor according to the invention therefore makes it possible to make the starter quickly operational in the event of icing of the contacts, it allows an initial supply under reduced motor voltage and it makes it possible to eliminate the harmful effects of contact bounces.

Claims (10)

Motor vehicle starter switch (10) of the type comprising a movable contact element (26), of electrically conductive material, the movements of which are controlled from a rest position to an active position in which it electrically connects the heads (40) of two fixed contact terminals (42), characterized in that at least one fixed contact terminal (42) is electrically connected to an auxiliary fixed contact (52) with which the movable contact element (26) comes to cooperate, for its electrical connection with the associated fixed terminal (42), in an intermediate position between its rest position and its active position. Contactor according to claim 1, characterized in that the auxiliary fixed contact (52) extends substantially parallel to the direction (XX) of movement of the movable contact element (26), and in that the movable element of contact (26) cooperates with the auxiliary fixed contact (52) along its displacement travel between said intermediate position and its active position. Contactor according to claim 2, characterized in that the auxiliary fixed contact (52) has a non-zero inherent electrical resistance (R) which determines a reduced value (l1, l3) of the intensity of the electric current which crosses the electric circuit which connects the two fixed contact terminals (42) when the movable contact element (26) cooperates with the auxiliary fixed contact (52). Contactor according to one of claims 2 or 3, characterized in that the movable contact element (26) is capable of cooperating with the auxiliary fixed contact by a lateral edge (62) and with the head (40) of the terminal fixed contact (42) associated by a transverse surface portion (50) substantially perpendicular to the direction (XX) of its movements and which is delimited by said lateral edge (62). Contactor according to one of Claims 3 or 4, characterized in that the auxiliary fixed contact (52) is produced in the form of an elastically deformable conductive strip (56, 60) which is deformed by the movable contact element ( 26) when the latter cooperates with the conductive strip (56), to guarantee the establishment of good electrical contact between these two elements (52, 56). Contactor according to claim 5, characterized in that the conductive strip (56) is produced integrally with an annular terminal (54) traversed by the body (46) of the fixed terminal (42) and which is in axial abutment against the annular face (44) for connection between the head (40) and the body (46) of the fixed terminal (42). Contactor according to any one of the preceding claims, characterized in that each of the two fixed contact terminals (42) is connected to an associated auxiliary fixed contact (52). Contactor according to any one of the preceding claims, characterized in that the heads (40) of the two fixed contact terminals (40) are arranged in the same plane perpendicular to the direction (XX) of movement of the movable contact element ( 26) which is produced in the form of a contact plate which extends in a plane substantially perpendicular to the direction of its movements. Contactor according to claim 8 taken in combination with claim 2, characterized in that the two auxiliary fixed contacts (52) extend over the same length. Starter (64) characterized in that it is equipped with a contactor (10) produced in accordance with any one of the preceding claims.

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