FR2705938A1 - Motor vehicle windscreen wiper comprising means for varying the value of the wiping force. - Google Patents

Abstract

The invention provides a wiper (10), in particular for a motor vehicle, of the type comprising a wiper arm (12) which is articulated on a drive head (16), and at least one spring ( 18) which is arranged between the drive head and the wiper arm, a first end (20) of the spring being connected to a point (22) of the wiper arm and the second end (24) of the spring being connected to the drive head (16), and of the type comprising means for varying the position of the second end of the spring relative to the articulation axis (XX) which comprise a drive rocker (38), a first branch (40) of which is connected to the outlet rod (56, 58) of a linear actuator (60), the body (62) of which is associated with the drive head (16), the second branch (42) of the drive rocker acting on the second end of the spring. The first branch (40) of the rocker comprises a drive cam profile (48) with which a cam follower element (50) cooperates arranged at the free end (56) of the output rod (58) of the actuator (60).

Description

The present invention relates to a wiper, in particular for a vehicle

  automobile, of the type comprising a wiper arm which carries at least one wiper blade and which is articulated, about an axis of articulation, on a drive head of the wiper arm. The drive head is reciprocated by a wiper shaft to

  to obtain a sweep of the window to be wiped.

  The wiper arm carries a wiper blade which is articulated and which is capable of wiping the glass surface such as for example a motor vehicle windshield. In order to obtain an effective wiping of the glazed surface, it is necessary that the wiper blade of the wiper is applied to the glazed surface to be wiped with a pressing force, or wiping force,

sufficiently large.

  For this purpose, at least one spring is known, such as for example a helical compression or tension spring, which is arranged between the drive head and the wiper arm and which applies a force to the latter. whose right support is not

  concurrent with the articulation axis of the wiper arm

  glass on the drive head so as to apply in fact to the wiper arm a wiping torque, also called nominal wiping torque, the

value is substantially constant.

  Due to the design of this device, the wiping blade is pressed during the scanning movement of the glass surface, but also in position

of the wiper.

  Due to the constancy of the nominal force

  that is applied to the blade when the wiper

  glass is in the rest position, the wiping blade tends to retain a residual deformation resulting from the crushing of its profile against the curved surface of the glass, the blade then no longer providing wiping

effective glass surface.

  It therefore appeared desirable to be able to vary the wiping force applied to the blade, in particular

  when the wiper is at rest.

  To this end, a towel has already been proposed.

  glass of the type mentioned above comprising means for varying the distance between the straight support of the force exerted by the spring and the axis of articulation of the wiper arm on the drive head. According to an embodiment described and shown in this document, a first end of the spring is connected to a point of the wiper arm and the second end of the spring is connected to the drive head, the means for varying the distance between the force support line and the articulation axis being means for varying the position of the second end of the spring with respect to the articulation axis which comprise a drive rocker rotatably mounted on the drive head, about a pivot axis parallel to the articulation axis of the wiper arm, a first branch of which is connected to the output rod of a linear actuator, the body of which is associated to the drive head, which moves in a direction perpendicular to the articulation and tilt axes, the second branch of the

  rocker acting on the second end of the spring.

  The means for controlling the tilting movements of the drive rocker described and shown in this document use a linkage which is relatively complex to produce and which presents risks of jamming and parasitic action on

  the linear actuator during the operation of the wiper

  ice. In order to remedy these drawbacks, the invention provides a wiper of the type mentioned above, characterized in that the first branch of the rocker comprises a drive cam profile with which a cam follower element arranged at the end cooperates.

  free from the actuator output rod.

  According to other features of the invention: - the cam profile is a groove formed in the first branch of the rocker in which is received an actuating finger fixed to the free end of the actuator output rod; - The cam profile comprises two end sections, each associated with an extreme position of the rocker relative to the drive head, and a connecting section; - Each end section is a straight section which, when the rocker occupies the extreme position associated with this end section, extends parallel to the direction of movement of the actuator output member; - The spring is a helical compression spring crossed by an orientation rod which defines the right force support, the first end of the spring bearing against a first bearing surface associated with the wiper arm while the second end of the spring bears against a second bearing surface associated with the orientation rod, one end of the orientation rod being connected to the second branch of the actuating rocker; - one end of the spring orientation rod is mounted articulated on the end of the second branch of the actuating rocker, around a

  axis parallel to the tilt axis.

  Other features and benefits of

  the invention will appear on reading the description

  detailed which follows for the understanding of which reference will be made to the appended drawings in which: - Figure 1 is a schematic view in partial longitudinal section of an example of a wiper produced in accordance with the teachings of the invention and which is shown in the rest position; - Figures 2 and 3 are sectional views along lines 2-2 and 3-3 of Figure 4; - Figure 4 is a partial top view of the wiper illustrated in Figure 1; - Figures 5 and 6 are sectional views along lines 5-5 and 6-6 of Figure 1; - Figure 7 is an enlarged view of the central part of the wiper illustrated in Figure 1; and - Figure 8 is a view similar to that of Figure 7 in which the wiper is illustrated in

position of use.

  The wiper 10 illustrated in the figures is essentially constituted by a wiper arm 12 whose body or casing 14 is mounted articulated on a drive head 16 about a geometric axis of articulation XX which extends in a direction substantially perpendicular to the general direction

  longitudinal of the wiper arm.

  The drive head 16 is designed to be connected to a drive shaft (not shown) which causes it to reciprocate around a geometric axis Y-Y which is substantially perpendicular to

the axis of articulation X-X.

  According to a known principle, a helical compression spring 18 is arranged between the wiper arm 12 and the drive head 16 so as to apply to the wiper arm a wiping torque which urges it

  counterclockwise considering Figure 1.

  For this purpose, the straight line D supporting the compression force exerted by the spring 18 is not concurrent with the axis XX and the value of the wiping torque applied to the wiper arm 12 is a function of the product. of the compression force of the spring 18 in the distance "d" between the straight line D and the axis XX. The spring 18 is crossed by an orientation rod 17 of which a first free end 19 is slidably mounted in a hole 21 formed at the end 22 of the rod which constitutes the body of the wiper arm

12.

  A first end 20 of the spring 18 bears against the face opposite the end 22 of the rod while the second end 24 of the spring bears against a support washer 26 fixed on the rod

Guidance 17.

  According to the invention, means are provided for varying the value of the wiping torque by varying the distance "d" between the straight support D and the hinge axis XX, by varying the orientation of the line D, i.e. the orientation

of the orientation rod 17.

  To this end, the second end 28 of the rod 17 has a form of yoke in which is received an actuating rod 30, the axis U-U of which is parallel to the axis of articulation X-X, and which is fixed on a

drive rocker 38.

  The drive rocker 38 is pivotally mounted around a geometric axis T-T which is parallel to the axis

X-X joint.

  The rocker 38 comprises a first branch 40 and a second branch 42 which extend in

  opposite directions on either side of the T-T axis.

  The second branch 42 carries, in the vicinity of

  its free end, the drive rod 30.

  The central part 44 of the rocker 38 is crossed by a hinge rod 46 which is rotatably mounted in the actuating head 16 as illustrated in particular in Figures 1 and 2, the position of the geometric axis of tilt TT being fixed by

  relation to the body of the drive head 16.

  The second branch 40 of the drive rocker 38 has a groove 48 forming a cam in which is received an actuating finger 50 which extends in a direction parallel to the axes of articulation X-X and of

T-T tilt.

  The drive finger 50 is fixed to the end of a plunger 52 which is slidably mounted in a guide sleeve 54, fixed inside the drive head 16, and which receives the threaded end 56 of the rotating output rod 58 of a motor 60 whose body 62 is fixed inside the drive head 16, so as to constitute a linear actuator of the

screw-nut type.

  The drive finger 50 therefore moves in sliding back and forth in a direction A

  perpendicular to the X-X and T-T axes.

  The groove 48 has a central section of

  link 64 and two end sections 66 and 70.

  The first end section 66 is a straight section which extends parallel to the direction of movement A of the plunger 52, as can be seen in FIG. 8 in which the rocker 38 is illustrated in its extreme position corresponding to the relief of the wiper arm 12 associated with the rest position of the wiper. Likewise, the end section 70 is a rectilinear section which, when the rocker 38 occupies its other extreme position illustrated in FIGS. 7, extends parallel to the direction A. Command and control means (not shown) allow the position of the output plunger 52 of the actuator to be varied between one and the other of the two extreme positions illustrated in the figures. In the so-called relief position illustrated in FIG. 8, the distance "d" between the geometric axis of articulation XX and the straight line D is minimum, the nominal wiping torque applied to the wiper arm 12 then being also minimal while, in the position illustrated in FIGS. 1 and 7, the distance "d" is maximum so as to apply maximum torque

  on the wiper arm 12.

  It is of course possible, without departing from the scope of the present invention, to control the actuator so that the plunger 52 occupies an intermediate position between these two extreme positions so as to apply a nominal torque to the wiper arm 12 between the minimum and maximum values. The rectilinear end sections 66 and 70 and their orientation, described above, make it possible to avoid forces being applied to the actuator in the two extreme positions. The displacements of the rod 58 can be controlled by means of a detection device such as the device 264 shown diagrammatically on the

  electric rheostat type figures.

  We now refer to FIG. 2 which shows an alternative embodiment of the invention in which the second branch 40 of the rocker comprises a track 148

  on which the actuating finger 50 slides.

  This track has a central portion 164 and two end portions 166 and 170 which correspond in direction substantially to the direction of the sections.

  64, 66 and 70 described above.

  The invention is not limited to the mode of

  realization which has just been described.

  It is particularly applicable in the case where the spring 18 is a helical compression spring. It is also possible to design numerous variants making it possible to obtain a more complex variation law of the value of the wiping torque, for example by modifying the profile of the section.

64 of the cam 48.

Claims (6)

  1. Wiper (10), in particular for a motor vehicle, of the type comprising a wiper arm (12) which carries at least one wiper blade and which is hinged, about an axis of articulation (X- X), on a head (16) for driving the wiper arm, and at least one spring (18) which is arranged between the drive head and the wiper arm for applying to the latter a force whose straight line support (D) is not concurrent with the articulation axis (XX) so as to apply to the wiper arm a wiping torque, a first end (20) of the spring being connected to a point (22) of the wiper arm and the second end (24) of the spring being connected to the drive head (16), and of the type comprising means for varying the position of the second end of the spring with respect to the articulation axis (XX) which comprise a drive rocker (38) rotatably mounted on the drive head (16) around a tilting axis (TT) parallel to the articulation axis (XX) of the wiper arm, a first branch (40) of which is connected to the outlet rod (52, 56, 58) d '' a linear actuator (60), the body (62) of which is associated with the drive head (16), which moves in a direction (A) perpendicular to the articulation and tilt axes, the second branch (42 ) of the drive rocker acting on the second end of the spring, characterized in that the first branch (40) of the rocker comprises a drive cam profile (48) with which cooperates a cam follower element (50) arranged at the free end (52) of the outlet rod (58) of the actuator (60).   2. Wiper according to claim 1, characterized in that the cam profile is a groove (48) formed in the first branch (40) of the rocker in which is received an actuating finger (50) fixed   at the free end of the actuator output rod.   3. Wiper according to one of claims 1   or 2, characterized in that the cam profile (48) comprises two end sections (66, 70), each associated with an extreme position of the rocker (38) relative to the drive head (16) and a stretch of link (64).   4. Wiper according to claim 3, characterized in that each end section (66, 70) is a straight section which, when the rocker (38) occupies the extreme position associated with this end section, s' extends parallel to the direction of movement (A) of the outlet member (52) of the actuator.   5. Wiper according to any one of   previous claims, characterized in that the   spring is a helical compression spring (18) crossed by an orientation rod (17) which defines the straight support (D) of the force, the first end (20) of the spring bearing against a first bearing surface ( 22) associated with the wiper arm while the second end (24) of the spring bears against a second bearing surface (26) associated with the orientation rod (17) and in that one end ( 28) of the orientation rod is connected to the second branch (42) of the actuation rocker.   6. Wiper according to claim 5, characterized in that said end (28) of the orientation rod (17) of the spring is articulated on the end (30) of the second branch (42) of the rocker d actuation, around an axis parallel (UU) to the axis tilt (T-T).