FR2632589A1 - DEVICE FOR DRIVING A WIPER ARM FOR MOTOR VEHICLES - Google Patents

Abstract

The device comprises a crank whose rotation is controlled in opposite directions and carrying a cylindrical pivot and a connecting rod articulated to the crank via a spherical pivot eccentrically mounted on the cylindrical pivot. Associated with the spherical pivot are means for reversing its eccentricity in order to achieve an additional stroke C of the arm B of the wiper E, in a hidden position of non-use, comprising a single bolt that can move by through the spherical pivot, and cam means between the spherical pivot and the crank for switching the bolt between two opposite positions of use, respectively of the connecting rod and of the crank.

Description

DEVICE FOR DRIVING A WIPER ARM FOR 2632589

MOTOR VEHICLES.

  The present invention relates as a whole to windshield wipers for motor vehicles, and relates more particularly to a device for driving a wiper arm by means of which, at the time of the control of its stop, this arm performs an additional stroke below the normal wiping field, until it stops in a low position where it

  is placed in the immediate vicinity of the lower side of the screen

breeze, disappearing from view. -

  To achieve this function, drive devices have been proposed, comprising a crank capable of being controlled in rotation in opposite directions and carrying a cylindrical pivot, a connecting rod articulated to the crank by means of a spherical pivot mounted eccentrically on the above cylindrical pivot, and coupling means associated with said spherical pivot to reverse the eccentricity with respect to the cylindrical pivot by the effect of the reversal of the direction of rotation of the crank. It is the reversal of the eccentricity of the cylindrical pivot which makes it possible, before the wiper arm stops, to obtain the stroke

  which brings this arm and the wiper blade

  glass associated with it, in the hidden lower position.

  In known drive devices of this type, described for example in patent GB-A-2 141 021, the coupling means for reversing the eccentricity of the spherical pivot relative to the cylindrical pivot normally comprise two engagement members to spring, one of which can move axially and works in conjunction with the crank, and the other can move radially and works in conjunction with the connecting rod, and relative cam devices, for switching couplings between the spherical pivot and respectively

the connecting rod and the crank.

  These solutions are of very complex and costly construction, in addition to their low operating reliability. The purpose of the present invention is to overcome

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  the drawback mentioned above, and to produce a drive device of the type specified above, consisting of a reduced number of components of a simpler and more economical production and assembly, and which is more capable ensure greater reliability and greater operational safety. According to the invention, this object is achieved by the fact that the coupling means associated with the spherical pivot to reverse the eccentricity with respect to the cylindrical pivot, by the effect of the reversal of the direction of rotation of the crank, comprise a pin single being able to move axially through said spherical pivot, between two opposite engagement positions, in the first of which, corresponding to the rotation of the crank in a first direction, it makes said spherical pivot integral in rotation with one of between said connecting rod and said crank, and in the second of which, corresponding to the rotation of the crank in a second direction, it makes said spherical pivot integral in rotation with the other of said crank and said connecting rod, and means for cam between said spherical pivot and said crank to carry out the switching of the bolt between said two positions of engagement at the time of the reversal of the

crank rotation.

  According to a preferred embodiment of the invention, the bolt is subjected to the action of a thrust spring which tends to push it axially towards the crank, and the cam means mentioned previously comprise a disc interposed between the crank and the spherical pivot, with a coefficient of friction with respect to the crank greater than the coefficient of friction with respect to the spherical pivot, and having an eccentric hole through which the cylindrical pivot passes; said disc maintaining the coupling in rotation with the connecting rod, of the first end of the bolt, in said first direction of rotation of the crank, against the action of the thrust spring, and having an opening which, in said first direction of rotation of the crank, is angularly offset with respect to an engagement seat formed in the crank; cutting means being provided to make the cam integral in rotation with the spherical pivot in said first direction of rotation of the crank and to allow rotation of the cam relative to the spherical pivot when the rotation of the crank in said second direction of rotation, until said cam opening, said crank engagement seat and the bolt are aligned with each other, allowing the engagement of the second end of the bolt in said retaining seat, under the action of

thrust spring.

  The aforesaid second end of the bolt and the engaging seat of the crank, advantageously have respective complementary ramp-shaped surfaces to allow reciprocal disengagement following the inversion of said second direction of rotation.

  towards said first direction of rotation of the crank.

  The invention will now be described in detail, with reference to the accompanying drawings, provided purely by way of nonlimiting example, in which: FIG. I is a schematic front elevation view of a windscreen wiper for motor vehicles, provided with a drive device according to the invention, FIG. 2 is an exploded perspective view of the drive device, FIG. 3 is a schematic plan view which shows the drive device during its normal operation, in four successive angular positions, FIG. 4 is a cross-sectional view on a larger scale along the line IV-IV of FIG. 3, FIG. 5 is a sectional view developed along the line -V of FIG. 4 FIG. 6 is a view similar to FIG. 3, which shows the drive device in three successive angular positions during a first phase of reverse operation, FIG. 7 is a cross-sectional view along line VII-VII of FIG. 6, FIG. 8 is a sectional view developed along the line VIII-VIII of FIG. 7, FIG. 9 is a view similar to FIGS. 3 and 6, which shows the device in three successive angular positions during a second phase of reverse operation, and FIG. 10 is a cross-sectional view on a larger scale along the line X-X of FIG. 9, and FIG. 11 is a view similar to FIG. 4, of a

  variant of part of the device.

  Referring first to FIG. 1, the reference P schematically indicates the windscreen of a motor vehicle, with which is associated a wiper E comprising a wiper blade S carried by an arm B which can be moved in an alternating angular movement along the windshield P, by means of a device

drive 1.

  As will appear in the following text, during the

  normal operation of device 1, the wiper blade

  window S carried by the arm B sweeps, on the windshield P, an angular field of magnitude A. When its stop is ordered, the wiper blade S performs, below the normal sweep field A, a stroke additional angular of magnitude C, placed at the level of the base of the windshield P, so as to be practically invisible

for the occupants of the vehicle.

  Referring now to more detail in FIG. 2, the drive device 1 comprises a control shaft 2, the rotation of which is controlled in a conventional manner by a reversible electric motor not illustrated (that is to say which can be operated in a direction of rotation or in the sense of rotation

  opposite), to which a crank is attached 3.

  The crank 3 carries a fixed cylindrical pivot 4, projecting orthogonally relative to the plane of The crank 3, on which is mounted eccentrically and so as to be able to rotate, a spherical pivot 5. In the example illustrated, the pivot 5 has a hole axial passing eccentric 6, crossed by the cylindrical pivot 4, which is locked axially relative to the spherical pivot 5, by means of an elastic retaining ring 7. In FIG. 4, the axes of the cylindrical pivot 4 and the spherical pivot 5 bear the references X and Y respectively, and their eccentricity is indicated by e. The spherical pivot 5 is in turn axially coupled so as to be able to rotate, in a capucbon 8 carried by a crank 9, in turn connected, in known manner, to the arm B of the wiper E. The reference 10 indicates a cam disc interposed axially between the spherical pivot 5 and the crank 3, and having an axial eccentric hole 11, aligned with the hole 6 of the spherical pivot 5, traversed so as to

  be able to rotate by the cylindrical pivot 4.

  The arrangement is such that the coefficient of friction occurring during sliding between the cam disc 10 and the spherical pivot 5 is less than the coefficient of friction during sliding between the cam disc 10 and the crank 3. This can be obtained for example , by making the spherical pivot 5 in a self-lubricating plastic material, while the disc at

  cam 10 and crank 3 are normally metallic.

  From the side of the cam disc 10 facing the spherical pivot 5 extends a projection 12, which engages so that it can slide in a curved slot 13

  located in the corresponding side of the spherical pivot 5.

  The arrangement is such that during normal operation of the wiper E, the projection 12 abuts against one end of the slot 13, and the cam disc 10 is rotated integrally with the spherical pivot 5. As will be seen in the following text, when the wiper E is turned on so

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  reverse, the projection 12 is free to fit into the slot 13, from which it follows that, due to the greater coefficient of friction between the disc 10 and the crank 3, an angular displacement of said cam disc 10 occurs , with respect to the spherical pivot 5. The cam disc 10 also has a peripheral notch 14, designed so as to operate jointly, as explained in the following text, with an engagement seat 15 formed in the surface of the crank 3, on which the disc 10 rests. As can best be seen in FIG. 5, the engagement seat 15, has at one end a ramp 15a,

  for the purposes explained in the rest of the text.

  The reference 17 indicates a targette mounted axially so as to be able to move through a passing opening 18 of the spherical pivot 5. The end of this targette 17 turned towards the side of the connecting rod 9, bearing, the reference 17a, is designed so to operate in conjunction with a retaining seat 19 formed inside the cap 8. The other end of the bolt 17, bearing the reference 17b, is in the form of an inclined ramp like the ramp 15a of the engaging seat of the crank 3, so as to operate jointly with it, according to the methods described

in the rest of the text.

  A helical compression spring 20 reacting between the spherical pivot 5 and a support arm 21 of the bolt 17 tends to push the latter in the direction

of the crank 3.

  The functioning of the drive device described

above is as follows.

  Referring first to FIG. 3, it is assumed that

  you want to control the normal operation of the wiper

  window E by means of the drive (by a special switch normally known as a lever) of the electric motor associated with the control shaft 2, in its normal direction of rotation indicated by the arrow H in Figs. 3 and 4. During normal operation, the arm B scans the scanning field A on the windshield P: the arrangement of the components of the device 1, shown in detail in FIGS. 4 and 5, is such that the eccentricity e is displaced on the side of the pivot 2, that is to say that the axis Y of the spherical pivot 5 is disposed radially inside, with respect to the axis X of the cylindrical pivot 4, in the starting position corresponding to the start of the angular scanning path A. This position is indicated in FIG. 3 by 0 '. The arrangement is further such that the notch 14 of the cam disc 10 is located in a position diametrically opposite the engagement seat 15 of the crank 3, and the pin 17 is held with its end 17a engaged in the seat 19 of the connecting rod 9, against the action of the spring 20. The projection 12 of the disc 10 abuts frontally against one end of the groove 13 of the spherical pivot 5 so that, during the entire rotation of the cylindrical pivot 4 with the crank 3, the cam disc 10 is integral in rotation with the spherical pivot 5, and its angular position relative to the bolt 17 therefore does not change. In this position, the notch 14 of the cam disc 10 is angularly offset with respect to the end 17b of the bolt 17, and, due to the engagement of the end 17a in the seat 19, the cap 8 and the connecting rod 9 are integral in rotation with the spherical pivot 5. The latter rotates

  obviously on the cylindrical pivot 4.

  As shown in Fig. 3, the arrangement described above does not change during the passage in the successive positions indicated, at 90-, 180 'and 270', except for the relative displacement between

  the crank 3 and the other components of the device 1.

  So, in practice, during normal operation of the wiper E, the cam disc 10 keeps constantly in rotation, linked, the connecting rod 9 and the spherical pivot 5, which means that each time that the arm B of the wiper E is placed in the initial position at 0 ', it is at the base of the sweep field A, and

  so at some distance from the bottom side of the screen

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  breeze P. When the stopping of the wiper E is controlled, a special automatic switch, not illustrated, takes care, according to a method already known, of reversing the direction of rotation of the electric motor, and therefore of the control shaft 2, as soon as the device 1 returns to the position of 0 '. The angular movement of the device 1 is then controlled, in the direction of the arrow marked with the reference

  K in Figs. 6, 7 and 9, for a full 360 'turn.

  This complete rotation has been divided, for the purposes of the explanation, into two successive phases from 0 to 180 '

  (Figs. 6 to 8) and from 180 to 0 * (Figs. 9 and 10).

  During the first phase, due to the reversal of the direction of rotation of the crank 3, an angular displacement of the cam disc 10 relative to the spherical pivot 5 occurs, due to its drive effected by the crank 3 and the makes the displacement of the projection 12 in the slot 13 of the spherical pivot 5. Passing from the position of 0 'to the position of 180', the cam disc 10 performs a corresponding angular displacement of 180 ', to the position shown in Figs. 7 and 8. In this position, the notch 14 of the cam disc 10 is placed in axial alignment, on the one hand with the engagement seat 15 of the crank 3, and on the other hand with the bolt 17 By the effect of the thrust exerted by the spring 20, the end 17b of the bolt 17 engages in the receiving cavity 15, while the end 17a emerges from the seat 18 of the cap 8 carried by the connecting rod 9. In this way, the coupling in rotation of the spherical pivot 5 is switched, it is released relative to the cap 8, and therefore relative to the connecting rod 9, and it is made solitary in rotation with the crank 3. As is clearly seen in Fig. 7, in the position at 180 ', the eccentricity e between the spherical pivot 5 and the cylindrical pivot 4 is diametrically opposite with respect to that which corresponds to the starting position at 0'; in other words, the Y axis of the spherical pivot 5 is located radially outside the axis

X of the cylindrical pivot 4.

  During the second phase of reverse rotation, shown in Figs. 9 and 10, the device successively rejoins the position at 270 'and the final position at 0'. During this rotation, the relative arrangement of its components does not change: the only relative angular movement in this phase is that occurring between the cap 8 of the connecting rod 9 and the spherical pivot 5. Consequently, while the device 1 stops in the final position at 0, the reversal of the eccentricity e described above allows the arm B of the wiper E to perform the additional stroke C, so as to place the blade S in the immediate vicinity of the windshield base P. When the wiper E is started again, by the effect of the rotation of the device I in the direction of the arrow H, when the position is reached at 180 ', the end 17b of the bolt 17 emerges from the receiving seat 15 of the crank 3, because of the inclined surface 15a and the corresponding conformation of the end 17b. The bolt 17 therefore rises against the action of the spring 20, by replacing itself with its end 17a engaged in the seat 19 of the cap 8, and it is held in this position by the effect of the successive rotation of the cam disc 10 by relative to the spherical pivot 5, to the contrast position between the appendix 12 and the end

of groove 13.

  Naturally, the construction details and the embodiments may be modified from what has been described and illustrated, without however

  go beyond the scope of the present invention.

  A possible variant is shown in FIG. 11, in which parts identical or similar to those described above are indicated by the same reference numbers. In this variant, the spherical pivot 5 (which is normally made of plastic material, like the cam disc 10) has, on the side of the crank 1 0, an annular protection in the form of

  axial appendage 5a, which surrounds the cam disc 10.

  This protection 5a advantageously protects the internal parts of the device against the penetration of external agents. In addition, in order to increase, in operation, the friction between the spherical pivot 5 and the cap 8 of the connecting rod 9, which is necessary for the drive of the first to be carried out by the second, so that the targette 17 can be released from the receiving seat 15, the spherical pivot 5 advantageously has an external circumferential groove 5b, placed on its largest diameter, and in which

  An O-ring made of 5c elastomeric material is housed.

  When the device 1 is assembled, this O-ring c is placed in frictional contact against the wall

internal side of the cap 8.

  In addition, the engagement arrangement of the bolt 17 could be reversed with respect to that which has been described with reference to the example illustrated, and could

  during normal operation of the wiper,

  glass E, the connection in rotation between the spherical pivot and the crank 3 by means of the bolt 17, and in the reverse rotation phase, the engagement between said bolt 17 and the connecting rod 9. Therefore, in practice, during normal operation, a slip appears between the spherical pivot 5 and the cap 8 of the connecting rod 9, while during the additional stroke of the reverse operation, the slip appears between the spherical pivot 5 and the cylindrical pivot 4. In this case, if R1 is the increase in the radius of the crank 3 necessary to obtain the additional angular stroke, the eccentricity necessary to obtain the desired increase R1 will be e = R1 / 2, and not

  step e = R1 as in the case described above.

  Finally, in the case of a wiper E with two brushes, the spherical pivot 5 could have a double configuration, that is to say with two cylindrical surface parts axially superimposed, for the connection of the two associated connecting rods with brooms. In this case, the general arrangement of the device I does not change, from the moment when a single bolt 17 is sufficient to reverse the eccentricity e of the two spherical pivots.

Claims (5)

  1. Device for driving a wiper arm comprising a crank whose rotation is capable of being controlled in the opposite directions, and carrying a cylindrical pivot, a bib hinged to the crank by means of a spherical pivot mounted eccentrically on the aforementioned cylindrical pivot, and coupling means associated with said spherical pivot to reverse its eccentricity with respect to the cylindrical pivot by effect of the reversal of the direction of rotation of the crank, characterized by the the fact that said coupling means comprise a single bolt (17) which can move axially through said spherical pivot (5) between two opposite engagement positions in the first of which, corresponding to the rotation of the crank (3) in a first direction CH), it makes said spherical pivot (5) integral in rotation with one of said connecting rod or crank (9, 3), and in the second of which, corresponding to the rotation of the crank (3) in a second direction (K) opposite to the first, it makes said spherical pivot (5) integral in rotation with the other of said crank or connecting rod (3, 9), and cam means (10) between said spherical pivot (5) and the crank (3) for switching the bolt (17) between said two positions of engagement at the time   reversing the rotation of the crank (3).   2. Device according to Claim 1, characterized in that the said bolt (17) is subjected to the action of a thrust spring (20) tending to push it axially towards the crank (3), and in that said cam means (10) comprise a disc (10) interposed between the crank (3) and the spherical pivot (5), with a coefficient of friction relative to the crank (3) greater than the coefficient of friction relative to the pivot spherical (5), and having an eccentric hole (11) through which the cylindrical pivot (4) passes; said disc (10) now, in said first direction of rotation (H) of the crank (3), a first end 13 2632589   (17a) of the bolt (17) cut in rotation with the ball (9) against the action of said thrust spring (20), and having an opening (14) which, in said first direction of rotation (H) of crank (3), is angularly offset relative to an engagement seat (15) located in the crank (3); cutting means (12, 13) being provided to make the cam (10) solid in rotation with the spherical pivot (5) in said first direction of rotation (H) of the crank (3), and to allow rotation of the cam (10) relative to the spherical pivot (5), when the rotation of the crank (3) is controlled in said second direction of rotation (K) until said opening (14) of the cam (10), said engagement seat (15) of the crank (3) and the bolt (17), allowing insertion of the second end (17b) that the bolt (17) in said engagement seat (15) under the action of said spring thrust (20).   3. Device according to claim 2, characterized in that said second end (17b) of the bolt (17) and said engagement seat (15) of the crank (3) have respective complementary surfaces in the form of a ramp ( 17b, 15a) to allow reciprocal disengagement following the inversion from said second direction of rotation (K) to said first direction of rotation (H) of the crank (3). -   4. Device according to claim 2, characterized in that the spherical pivot (5) has, on the side of the crank (3) an annular protective appendage   (5a) which contains the above-mentioned cam disc (10).   5. Device according to claims 2, characterized in that the spherical pivot (5) has an external circumferential groove (5b) in which is housed an O-ring made of elastomeric material (5c), and in that the connecting rod (9 ) has a cap member (8) engaged on the spherical pivot (5) and the internal wall of which is in frictional contact with said ring toric (5c).