VARIABLE-SWEEP WINDSCREEN WIPER FOR VEHICLES

Abstract: A windscreen wiper (1) is described, of the type in which the wiper blade support arm (4) is mounted slidable on an arm support member (7) which is rotated alternately in opposite directions by a rotatable pin (3) of a drive motor (2); the support member (7) is mounted idly about the pin (3) and receives its motion from this latter by way of a transmission comprising gears (12, 16, 18) and a pinion (14) rigid with said pin (3); the wiper blade support arm (4) is moved by a bar (20) hinged to it and provided with an internally toothed track (30) defining an endless path comprising two parallel rectilinear branches which are joined together by curved portions, and are selectively engaged by said pinion (14) in order to move the bar (20) relative to this latter.

Description: VARIABLE-SWEEP WINDSCREEN WIPER FOR VEHICLES This invention relates to a variable-sweep windscreen wiper for a vehicle, of the type in which the wiper blade support arm is slidably carried by an arm support member, which is rotated by the windscreen wiper drive pin. This type of windscreen wiper is particularly suitable for use as a single-blade windscreen wiper for wiping a larger vehicle windscreen surface. In known windscreen wipers of the aforesaid type, the traversing movement of the wiper blade support arm on the arm support member is obtained from the rotary movement of the arm support member itself, by way of complicated transmissions of the lever mechanism type (connecting rod - crank). This type of transmission is subject to jamming, and is relatively bulky. The object of the invention is to provide a vehicle windscreen wiper of the aforesaid type, which is of small overall size and of reliable operation. This object is attained according to the invention by a vehicle windscreen wiper, of the type comprising an arm carrying at a first end a wiper blade holder, and an arm support member rotating about an axis and slidably carrying said arm in such a manner that this latter is angularly rigid with said arm support member but radially mobile with respect to said axis, characterised by comprising a rotatable drive pin provided with a toothed pinion in an angularly rigid manner, transmission-means for transmitting the rotary motion of said rotatable pin to said arm support member, which is mounted idly about said rotatable pin, a control bar hinged to the second end, distant from said first end, of said arm and provided with an internally toothed longitudinal track defining an endless path comprising at least one pair of parallel rectilinear branches joined together by respective curved end portions, and guide means for causing said toothed pinion to engage with one of said branches and for guiding the trajectory of the consequent movement of said pinion relative to said bar along said endless path defined by said track. The invention will be more apparent from the non-limiting description of one embodiment thereof given hereinafter with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of the windscreen wiper acording to the invention; Figure 2 is a partly sectional elevation of the windscreen wiper of Figure 1; Figure 3 is an underside plan view of a detail of the windscreen wiper of Figure 1 to an enlarged scale; and Figure 4 is a section on the line IV-IV of Figure 3. In Figures 1 and 2, the reference numeral 1 indicates overall a windscreen wiper for a vehicle of any known type, not shown for simplicity, and particularly suitable for wiping large zones of a respective vehicle window, also of known type and not shown for simplicity, for example the vehicle rear window or windscreen. The windscreen wiper 1 comprises a reversible electric motor 2 of known type and operating a rotatable drive pin 3, a wiper blade support arm 4 carrying rigidly at one of its ends 5 a wiper blade holder 6 of known type, and an arm support member 7 rotating about the axis of the pin 3 and carrying the arm 4 in a slidable but angularly rigid manner, that end 8 of this latter distant from the end 5 being slidably housed within a quadrangular guide sleeve 9 formed integrally with the arm support member 7 in correspondence with the projecting end 10 thereof. The arm support member 7 is mounted idly on the motor 2 about a collar 11 coaxial to the pin 3, and is integral with a toothed sector 12 formed on its end 13 distant from the end 10. A pair of mutually coaxial and angularly rigid gears 16 and 18 are carried idly by the motor 2, eccentrically to the pin 3, on a pin 15 disposed near the pin 3, which is provided with an angularly rigid toothed pinion 14, and engage respectively with the toothed pinion 14 and the toothed sector 12, to thus ensure transmission of the rotary motion of the rotatable pin 3, produced by the motor 2, to the arm support member 7 which consequently, according to the direction of rotation of the pin 3, moves selectively along a circular curved trajectory in the directions shown by the arrows in Figure 3, to drag with it the arm 4 constrained within the sleeve 9, so that the arm 4 undergoes the well-known typical reciprocating sweeping movement of windscreen wipers, which enables the wiper blade, of known type, not shown for simplicity, and carried by the wiper blade holder 6 to wipe the said window, not shown. According to the invention, the windscreen wiper 1 also comprises a control bar 20 hinged to the end 8 of the arm 4 by a pin 21 idly constrained in a respective bore 22 in the reduced-thickness end 23 of the bar 20. The bar 20 is provided lowerly, towards the motor 2, with a slot-shaped longitudinal cavity 25 with rounded opposing ends 26, and bounded peripherally by a lower edge 27 provided with internal toothing 28, and provided internally with a central longitudinal rib 29 rounded at its ends and having a height preferably equal to the height of the untoothed root portion of the edge 27. The cavity 25 and rib 29 define an internally toothed annular track 30 defining an endless path, which comprises a pair of mutually parallel, longitudinal rectilinear branches 31 separated by the rib 29 and joined together by respective curved portions constituted by the ends 26. The toothing 28 is arranged to engage the pinion 14 in order to transmit the rotary motion of this latter, converted into reciprocating translational motion, to the bar 20 so that this latter becomes mobile longitudinally along its own axis to thus cause the arm 4 to move relative to the arm support member 7. In this respect, suitable guide means maintain one of the toothed branches 31 in selective engagement with the pinion 14, and the curved portions 26, also provided with the toothing 28, ensure passage of the pinion 14 without discontinuity from one rectilinear branch 31 to the next. These guide means comprise an inner side wall 32 of the track 30 (Figure 4), this wall being defined by the rib 29, and a cylindrical endpiece of reduced diameter 33 provided on the rotatable pin 3 and projecting from the pinion 14 towards the base of the cavity 25 to cooperate laterally with the side wall 32. The rib 29 also cooperates with the front end of the pinion 14 by abutting against it, and the bar 20 is kept in engagement with the pinion 14 and with the other elements of the windscreen wiper 1 by a casing 40 composed of two half-casings 41, and housing the motor 2 and all the mobile members of the windscreen wiper 1, such as the gears 16 and 18, the bar 20 and part of the arm 4, and the end 13 of the member 7. Only the power supply cable for the preferably electric motor 2 and the end 10 of the member 7 emerge from the casing 40, so that the entire windscreen wiper 1 is supported by the casing 40 and can therefore be mounted with this latter on a vehicle by means of a single operation. In order to ensure the operation of the described windscreen wiper 1, the motor 2 must be able to reverse the direction of rotation of the pin 3 which it operates, only when the pinion 14 is located in correspondence with that curved portion 26 defining the end of the track 30 facing the slidable arm 4, or facing the sleeve 9. On the assumption that this condition is satisfied, the operation of the windscreen wiper 1 is as follows (Figure 4). When the pinion 14 is rotated in the direction of the arrow, it engages with one of the branches 31, which act as racks, to cause the bar 20 to translate relative to the arm support member 7 in the direction of the arrow, and consequently it moves relative to the bar 20 with a relative movement the trajectory of which is indicated by the arrows and follows the shape of the endless path defined by the track 30. In this respect, when the bar 20 moves towards the sleeve 9, the pinion 14 approaches that curved portion 26 at the opposite end, and when it reaches it it is guided by the endpiece 33, cooperating with the rib 29, so that it engages with the other branch 31, on the opposite side to the preceding. Consequently, as the pinion 14 continues to rotate in the same direction, but as the side of the toothing 28 with which it engages has changed, the movement of the bar 20 becomes reversed, and it moves towards the gears 15 and 18 to cause the pinion 14 to approach the curved portion 26 facing the sleeve 9, in correspondence with which the bar 20 completes its to-and fro movement, and the pinion 14 returns to the preceding branch 31. From this position, the pinion 14 is ready to again travel along the track 30 either in the same direction or in the opposite direction if the rotation of the pinion 14 is reversed, to in either case cause the bar 20 to undergo reciprocating translational movement in a manner analogous to that heretofore described, with maximum elongation in correspondence with that portion 26 facing the sleeve 9 and minimum elongation in correspondence with the opposite portion 26. It is therefore apparent that because of its connection both to the bar 20 and to the member 7, the arm 4 moves with a composite movement due to its rotation about the pin 3, rigid with the arm support member 7, and to its simultaneous translation, rigid with the bar 20, and relative to said arm support member 7. This movement therefore enables the wiper blade holder 6 to describe an arc of variable radius, which is a maximum at the upper corners of the window to be wiped, analogously to other known variable-sweep windscreen wipers. However, in contrast to known windscreen wipers, the windscreen wiper 1 enables the wiper blade holder 6 to undergo a symmetrical trajectory, to ensure equal cleaning of the two halves of the window, which is essential when used as a single-blade windscreen wiper, ie as the only windscreen wiper cleaning the vehicle windscreen. Moreover, the translational movement is not subject to jamming, and the system of transmission members used is of small overall size, of low cost and of very simple production and assembly. Finally, the windscreen wiper 1 can be used on windows of different shapes by simply replacing the bar 20 by another of different length, and/or with a track 30 having a different number of teeth. The advantages of the invention are apparent from the aforegoing description, and it is also apparent that modifications can be made to the illustrated embodiment, but without leaving the scope of the present invention.

Claims: PATENT CLAIMS 1. A vehicle windscreen wiper (1), of the type comprising an arm (4) carrying at a first end a wiper blade holder (6), and an arm support member (7) rotating about an axis and slidably carrying said arm (4) in such a manner that this latter is angularly rigid with said arm support member (7) but radially mobile with respect to said axis, characterised by comprising a rotatable drive pin (3) provided with a toothed pinion (14) in an angularly rigid manner, transmission means (12, 16, 18) for transmitting the rotary motion of said rotatable pin (3) to said arm support member (7), which is mounted idly about said rotatable pin (3), a control bar (20) hinged to the second end, distant from said first end, of said arm (7) and provided with an internally toothed longitudinal track (30) defining an endless path comprising at least one pair of parallel rectilinear branches joined together by respective curved end portions, and guide means (29) for causing said toothed pinion (14) to engage with one of said branches and for guiding the trajectory of the consequent movement of said pinion (14) relative to said bar (20) along said endless path defined by said track (30). 2. A windscreen wiper (1) as claimed in claim 1, characterised by further comprising a reversible operating motor (2) which rotates said rotatable pin (3) and is arranged to reverse its direction of rotation only when said pinion (14) is located in correspondence with that of said curved portions which defines the end of said track (30) facing said arm (4). 3. A windscreen wiper (1) as claimed in claim 1 or 2, characterised in that said arm support member (7) and said transmission means are both idly carried by a support (2) surrounding said rotatable pin (3), said arm support member (7) being disposed coaxial to said rotatable pin (3), and said transmission means comprising a toothed sector (12) formed on that end (13) of said arm support member (7) distant from said arm (4), and a pair of mutually coaxial gears (16, 18) mounted eccentric to said rotatable pin (3), a first of said gears (16) engaging said toothed pinion (14), and the other gear (18) engaging said toothed sector (12) of the arm support member (7). 4. A windscreen wiper (1) as claimed in claims 2 and 3, characterised in that said support is constituted by said reversible motor (2). 5. Awindscreen wiper (1) as claimed in one of the preceding claims, characterised in that said guide means comprise an inner side wall of said track (30) defined by a lower rib (29) provided on said control bar (20) and cooperating frontally with said pinion (14) by abutting thereagainst, and laterally with a cylindrical reduced-diameter endpiece of said rotatable pin (3), said rib (29) dividing said two rectilinear branches of said track (30) from each other, this latter being defined by said rib (29) and by a lower cavity (25) of said control bar (20), bounded by an internally toothed edge (27) and containing said rib (29).

Inventors: DI GIUSTO, NEVIO
Applicants: FIAT AUTO S.P.A.
Application year: 1986
Main classification: B60S1
IPC codes: B60S1